Moparts

What is Proper Valvetrain Geometry?

Posted By: MadMopars

What is Proper Valvetrain Geometry? - 10/14/14 04:36 AM

What is Proper Rocker Arm Geometry? I used to believe you could buy a set of rocker arms, throw pushrods in and call it a day. This would be incorrect, or so it now seems... I am curious to know the following.

1.) What do you guys consider to be proper rocker arm geometry and why?

2.) What brand and/or style Rocker Arm do you recommend be utilized to achieve proper rocker geometry and why?
Posted By: clonestocker

Re: What is Proper Rocker Arm Geometry? - 10/14/14 04:43 AM

What direction are you heading Trent? BTW: Are your Mom and Dad doing any of the Cruising Speedway thing on Saturday Night?
Posted By: skj283

Re: What is Proper Rocker Arm Geometry? - 10/14/14 05:23 AM

i'll throw in my 2 cents. I look for a narrow sweep, not a centered sweep if you are doing the sharpie on the valve stem and turning the engine over. the wider the sweep, the more waste of lift, and from what I understand, side loading of the guides. I made a tool to measure the sweep across the valve and its really eye opening to see what a pretty insignificant change in pushrod length does to the width of the sweep. that being said, I don't have lot of experience with shaft rockers, primarily sbc and sbf stuff is what I have done. but im working on my first shaft motor so I am looking forward to seeing how what I have learned applies to these engines.
Posted By: BradH

Re: What is Proper Rocker Arm Geometry? - 10/14/14 01:43 PM

Posted By: clonestocker

Re: What is Proper Rocker Arm Geometry? - 10/14/14 04:41 PM

I'll take a simple stab at this.

The center line of the trunion (sp)and roller tip perpendicular to the center line of valve stem at mid lift. Anybody?
Posted By: Monte_Smith

Re: What is Proper Rocker Arm Geometry? - 10/14/14 04:53 PM

Quote:

What is Proper Rocker Arm Geometry? I used to believe you could buy a set of rocker arms, throw pushrods in and call it a day. This would be incorrect, or so it now seems... I am curious to know the following.

1.) What do you guys consider to be proper rocker arm geometry and why?

2.) What brand and/or style Rocker Arm do you recommend be utilized to achieve proper rocker geometry and why?


What brand and/or style Rocker Arm do you recommend be utilized to achieve proper rocker geometry and why? Has little to do with brand or style of rockers............has WAY more to do with consistency or lack there of in cylinder head castings with built in pedestals. Bottom line if the pedestals are not right, NO rocker or diff pushrod length is going to FIX it. BEST way to fix it, is machine the head flat and put the pedestals where they NEED to be. That's a lot or work and or above the heads of most novice builders though

Monte
Posted By: Quicktree

Re: What is Proper Rocker Arm Geometry? - 10/14/14 05:21 PM

my question is why even worry about it? I have never checked nor really give a flip if they are off a little. unless you are doing something very specific or searching for every bit of HP you can get what does it matter? there are thousands of motors built and last for a long period of time with no problems.
Posted By: AndyF

Re: What is Proper Rocker Arm Geometry? - 10/14/14 05:25 PM

I wrote a full chapter on valvetrains in my big block Mopar book. I'd suggest starting there. I included a bunch of pictures showing how different brands of rocker arms are different lengths and therefore fit differently on the various Mopar cylinder heads.
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/14/14 06:11 PM

I have seen many sources state the following theories: Mid lift 90 degree theory is optimal and minimal sweep is desired. Both of these do provide benefits. However, there are other aspects that are overlooked and must be considered. Just because you have mid lift 90 degree geometry, a tight sweep pattern and a well positioned roller on the stem DOES NOT mean you have optimal geometry. I have since seen that there are other factors that MUST be considered before you can establish proper valvetrain geometry for your application.

Why does proper geometry matter? Because it is without a doubt relative to performance. To what extent though... It appears as though Mid lift theory will only get you so far. Perhaps, so far is stability which it does provide. However, I have by definition established this previously stated "Optimal Geometry" in my application and as such I have now sacrificed performance to a degree...

Thoughts???
Posted By: BradH

Re: What is Proper Valvetrain Geometry? - 10/14/14 06:14 PM

Quote:

... I have by definition established this previously stated "Optimal Geometry" in my application and as such I have now sacrificed performance to a degree...



Care to explain more re: this statement?
Posted By: Monte_Smith

Re: What is Proper Rocker Arm Geometry? - 10/14/14 06:31 PM

Quote:

my question is why even worry about it? I have never checked nor really give a flip if they are off a little. unless you are doing something very specific or searching for every bit of HP you can get what does it matter? there are thousands of motors built and last for a long period of time with no problems.


Thousands of motors out there running as well that never have the clearances checked either...........do you advocate that as well?

Are we building motors RIGHT......or are we just throwing them together and hoping for the best.........or are we just doing something in between.

Right is right.....half azz is half azz

Monte
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/14/14 06:36 PM

Quote:

Quote:

... I have by definition established this previously stated "Optimal Geometry" in my application and as such I have now sacrificed performance to a degree...



Care to explain more re: this statement?




Utilizing the 90 degree mid lift theory in my application has resulted in increased valvetrain stability. It has also caused a loss of performance. It will now rev higher without adverse effects, but E.T has slowed regardless of shift point. Power has been sacrificed for stability.
Posted By: Monte_Smith

Re: What is Proper Valvetrain Geometry? - 10/14/14 06:53 PM

Quote:

Quote:

Quote:

... I have by definition established this previously stated "Optimal Geometry" in my application and as such I have now sacrificed performance to a degree...



Care to explain more re: this statement?




Utilizing the 90 degree mid lift theory in my application has resulted in increased valvetrain stability. It has also caused a loss of performance. It will now rev higher without adverse effects, but E.T has slowed regardless of shift point. Power has been sacrificed for stability.


Has this been corroborated on a dyno, as in you KNOW you make less power or is the car just running a little slower ET.............Where on the track did it slow? Is it early, in the middle or on the top end. If the car runs the same speed it ran before, it makes the same power. You just may not be getting it down as consistently or as easily as you were before.

My point is that it seems hard for me to believe that MORE revs and better stability has cost you power

Monte
Posted By: BradH

Re: What is Proper Valvetrain Geometry? - 10/14/14 07:05 PM

Quote:

Quote:

Quote:

Quote:

... I have by definition established this previously stated "Optimal Geometry" in my application and as such I have now sacrificed performance to a degree...



Care to explain more re: this statement?




Utilizing the 90 degree mid lift theory in my application has resulted in increased valvetrain stability. It has also caused a loss of performance. It will now rev higher without adverse effects, but E.T has slowed regardless of shift point. Power has been sacrificed for stability.


Has this been corroborated on a dyno, as in you KNOW you make less power or is the car just running a little slower ET.............Where on the track did it slow? Is it early, in the middle or on the top end. If the car runs the same speed it ran before, it makes the same power. You just may not be getting it down as consistently or as easily as you were before.

My point is that it seems hard for me to believe that MORE revs and better stability has cost you power

Monte



And if the before and after tests supposedly showing a decrease in performance weren't in identical conditions -- or if the conditions for both test sessions aren't known so that the appropriate correction factors can be applied for an apples-to-apples comparison --, you really can't say whether it's slowed down or not.
Posted By: John_T_Brown

Re: What is Proper Valvetrain Geometry? - 10/14/14 07:16 PM

You asked for it! I gathered info from here and there (mostly from Racer Brown)and put it together into a document that everyone can read and learn from. This document was created in September of 1999 but everything in it is still relevant today, Enjoy!

ROCKER ARM (Valve train)GEOMETRY

Rocker arm geometry is an expression that is frequently heard but seldom understood in the area of high-performance engines, or anywhere else, for that matter. It's a fair guess that only about one person in a thousand or more does anything about it, even superficially. Nevertheless, it is of the utmost importance in any high-performance engine, and this importance increases as valve lifts continue to increase.

Rocker arm geometry is defined as the relationship of the rocker arm tip to the valve stem tip through the valve opening and closing cycle. This is seen as a point of tangency where the radiused rocker arm tip contacts the flat surface of the valve stem tip. This sounds simple enough, and it is, but unless one has a grasp of the fundamentals, correcting the rocker arm geometry can be downright frustrating and difficult. It is time-consuming at best, but there's free horsepower here, and that's the best kind, as well as making life very much easier on the entire valve train, plus a few extra revs that normally cannot be found.

Ideally, rocker arm geometry is correct when the center-point of the rocker arm tip radius coincides with the centerline of the valve stem at EXACTLY one-half valve lift. Again, this sounds simple enough, but nearly everything that is touched in the build-up process of an engine affects rocker arm geometry, usually for the worse. The base radius of the cam lobes (one half the base circle), effective lifter length, pushrod length, cylinder block and/or cylinder head decking operations, the depth of the valve seats in the cylinder heads, the dimension from the valve stem tip to the valve seat in the cylinder heads, plus the "fixed" hardware of the rocker arm stands and shafts, and total valve lift, all combine, for better or worse, to affect rocker arm geometry.

Rocker arm geometry needs help when one or more of the following symptoms appear in an operational engine: Increased oil consumption and/or vacuum leaks due to eggshaped valve guide bores; scuffing of either or both rocker arm tips or valve stem tips when there is adequate lubrication; scuffing of pushrods or rocker arms at the pushrod ends of the rockers when there is adequate lubrication; scuffing of rocker arm balls and/or sockets in the case of engines with ball-type rocker arms; premature wear of rocker arm bushings in the case of engines with fixed-pivot shaft-type rocker arms; in extreme cases, bent valves, bent pushrods, broken rocker arms. Any or all of these symptoms can be caused by excessive forces required to open and close the valves due to the higher friction generated by incorrect rocker arm geometry.

The first area of correction is the dimension from the valve stem tips to the valve seats in the cylinder heads. This point is simplified during engine build-up by being certain that the depth of all valve seats in the cylinder heads is exactly the same, as measured with a depth micrometer from the cylinder head gasket face to the valve seats. There will be a difference between the depths of the intake valve seats and the exhaust valve seats because of the differences in valve seat diameter and the angles involved. However, the depth of all intake valve seats must be the same and the depth of all exhaust valve seats must be the same, but not necessarily the same as each other. Install an inner valve spring, valve locks and spring retainer on each valve so the valves will remain seated. Using a small precision square and a fairly long steel straightedge placed on the valve stem tips, determine which valve along the line of valves in the cylinder head is the shortest. With a depth micrometer, measure from the top of the straightedge to the top of each valve stem tip. These readings will give directly and accurately the differences in valve stem length.

Each valve and valve seat must be numbered before disassembly so that each valve will go back into the same valve guide bore. Log the amount that each valve stem is longer than the shortest one, then remove the valves from the cylinder heads.

If the intake valves are in a different plane from the exhaust valves, as in a hemispherical combustion chamber, the measurement and logging of valve stem lengths must be repeated. In this case, all intake valve stem lengths must be equalized, as must all exhaust valve stem lengths, but again, the intake valve stem length does not have to be the same as the exhaust valve stem length.

Next, the valve stem tips must be ground off squarely and accurately to match the shortest valve or valves. This must be done in a good valve refacing machine, with a freshly-dressed grinding wheel and with the valve stem located so the finished valve stem tip is exactly perpendicular to the valve stem. The finished valve stem tip must be as smooth as possible and dead flat.

Reassemble the cylinder heads with the valves, inner valve springs, valve locks and spring retainers, with each valve in its original valve guide bore. With the straightedge and depth micrometer, make a repeat measurement from the top of the straightedge to the valve stem tips. Ideally, they should be exactly the same as the shortest valve stem. Things of this nature are rarely ideal, so an acceptable target is if all valve stem lengths are within plus-or-minus .005 inch of each other. This is the time to correct any and all out-of-tolerance valve stem length discrepancies.

Install one cylinder head on the cylinder block with a used but clean cylinder head gasket. The cylinder head must be torqued down properly, as in final assembly, but we're not there yet. Install the camshaft, lifters, pushrods, rocker arms and related hardware for number one cylinder. At this point, the outer valve springs are not yet required and should be left off to make rotation of the camshaft easier. Place the spindle of a one-inch stroke dial indicator on the spring retainer (NOT on the rocker arm) of number one intake valve. Preload the dial indicator to something more than total valve lift and make certain that the spindle of the indicator is parallel to the valve stem in both longitudinal and transverse planes. Rotate the camshaft so that the lifter for number one intake valve is on the center of the heel of the cam lobe (directly opposite maximum valve lift). Watching the indicator, tighten the valve adjusting screw so the valve is off the seat by .002 to .003 inch, then zero the indicator dial. Rotate the camshaft so that maximum valve lift shows on the indicator and log, this number. Rotate the camshaft again until the indicator shows the valve is at exactly one-half maximurn valve lift.
Now very carefully observe the relationship of the rocker arm tip to the valve stem tip. Good light is essential, and a piece of white paper held behind the valve will help. Ideally, at exactly one-half valve lift, the rocker arm tip must contact the valve stem tip at the exact center of the valve stem.

If; at one-half valve lift; the rocker arm tip contacts the valve stem tip outboard (toward the outside of the engine, the pushrod is too long or the rocker shaft stands are too high. Conversely, if the rocker arm tip contacts the valve stem tip inboard (toward the center) of the engine, the pushrod is too short or the rocker shaft stands are too low. Unfortunately, for the most part, this must be an "eyeball" test, but good lighting, very careful observation and effort applied toward honesty of the evaluation rather than expediency will be long steps in the right direction.

If' the rocker arm tip appears" to contact the valve stem tip, very close to the center of the valve stem at one-half valve lift, there is one simple check that will tell if it's close enough. Rotate the camshaft back to zero or minimum lift and loosen the valve adjusting screw. Slip a piece of tissue paper between the rocker arm tip and the valve stem tip, then tighten the valve adjusting screw until there is about .002 to .003 inch lash. Rotate the camshaft through the full valve opening and closing cycle and remove the tissue paper. If the imprint of the rocker arm tip in the tissue paper is consistent and even, lock it up and be glad that corrections are not necessary. On the other hand, if the tissue paper is torn or is smashed to near-transparency at one point, this very strongly suggests that corrective actions are required. This process must be repeated on number one exhaust valve.

Theoretically, the rocker arm tip should roll across the valve stem tip as the valve opens and closes with no side loads being imposed upon the valve stem by the rocker arm. The rocker arm tip radius is therefore very critical, being a function of the lever arm length as the rocker arm swings through an arc during the valve opening and closing cycle. The lever arm length constantly varies as the rocker arm is in motion. The lever arm length is measured from the pivot point of the rocker arm to the contact point on the valve stem tip in a plane that is perpendicular to the centerline of the valve stem. Therefore, the lever arm length is one dimension at zero lift and another longer dimension at maximum lift, and at exactly one-half lift, the lever arm length will be somewhere between the minimum and maximum lever arm lengths.

As a point of clarification, the rocker arm tip radius is defined as that found on stock-type rocker arms. However, everything still applies to the so-called "roller tip" rocker arms made by specialty manufacturers. In these cases and in spite of contrary thoughts and words, the rocker arm geometry problem is made worse instead of better for two distinct reasons. First, the radius of the roller tip that is inserted in the end of the rocker arm is wrong for proper rocker arm geometry because these rollers are always too small in diameter. Second, high-speed motion picture studies have shown beyond any doubt that the roller rarely, if ever, actually rolls across the valve stem tip. This occurs because of too-small roller tip diameter, there being an insufficient mechanical couple to make the roller tip roll smoothly. If some rolling occurs, it is jerky and inconsistent.

The roller tip rocker arm is thought to be a "cure-all" in the area of rocker arm geometry, and not only does it fail in this respect but, as pointed out, it makes matters worse. If this type of rocker arm is to be used, it is absolutely essential that the rocker arm geometry be as near to perfect as possible in order to minimize the effects of a roller tip that is too small.

Correcting rocker arm geometry, in the case of engines with fixed-pivot shaft-type rocker arms, will involve either raising or lowering the rocker shaft stands. If the rocker arm tip contacts the valve stem tip more toward the outboard side of the engine, the rocker shaft stands must be lowered. If contact is made more toward the inboard side of the engine, the rocker shaft stands must be raised, as previously stated.

The amount the rocker shaft stands must be raised or lowered must be the result of a judicious "guesstimate." Raising the stands presents no particular problem because the stands can be shimmed with washers or shim stock for a trial fitting. Usually, from .030 to .045 inch is a good starting point. With the rocker shaft stands blocked up and torqued, take another long look at the rocker arm tip contact in relation to the valve stem tip. When the final spacer thickness has been determined, permanent spacers must be made up to the same size and shape as the bottoms of the rocker shaft stands where the stands bolt to the cylinder heads. Starrett ground flat stock is excellent for this purpose because of the wide variety of widths, lengths and thicknesses available, plus this material is surface ground on both sides to assure flatness and parallelism. All hold-down bolt holes, dowel pin holes, lubrication holes, etc., must be duplicated in size and location on the permanent rocker shaft stand spacers.

On the other hand, if the rocker shaft stands must be lowered to correct the rocker arm geometry, then metal must be removed from the bottoms of the stands. This is best done in a surface grinder or a milling machine, properly located and clamped so that all rocker shaft stands can be done in one set-up. Any metal that is removed cannot be easily added later, so it is essential that the finish cut be parallel in both planes to the original bottom surfaces of the rocker shaft stands. Initially, a cut of from .030 to .040 inch is a good starting point for a trial fit. The finished surfaces must be smooth, flat and free of burrs.

If the rocker arm geometry requires only a slight correction, this can usually be accommodated easily with a special-length pushrod, and raising or lowering the rocker shaft stands can be forgotten. If it appears that the rocker shaft stands should be raised, a longer pushrod is required; and, conversely, if it appears that the rocker shaft stands should be lowered, a shorter pushrod is required. This condition can be verified by the position of the rocker arm adjusting screw in the rocker arm. The threaded segment of the rocker arm adjusting screw should be centered in the rocker arm with the valves adjusted to the proper valve lash. If a locknut is used on the rocker arm adjusting screw, it must be removed for this observation. If the rocker arm adjusting screw must be backed out so that there are more threads visible on the top of the rocker arm than there are below it, the pushrod is too long. If the opposite is true, or if there aren't enough threads on the top of the rocker arm to give full-length contact for the rocker arm adjusting screw locknut, then the pushrod is too short. In any case, the pushrod must contact only the rocker arm adjusting screw, and not the rocker arm itself, throughout the full valve opening and closing cycle.

Again, changing the pushrod length in a fixed-pivot shaft-type rocker arm engine will not make a major change in rocker arm geometry, but it will definitely help. Any major changes must be made by raising or lowering the rocker shaft stands.

In engines with ball-type rocker arms, the ONLY way the rocker arm geometry can be corrected is with special length pushrods, assuming that the valve stem lengths have been equalized as previously described.

How much longer or shorter should the pushrod be in order to correct the rocker arm geometry? A good question deserving a good answer. The easy way is to have an adjustable pushrod made so that the effect of lengthening or shortening the pushrod can be very carefully observed in relation to rocker arm geometry. Then, when the rocker arm geometry is just exactly right, the overall length of the adjustable pushrod must be very carefully measured so non-adjustable pushrods can be made up to exactly duplicate this length. If the intake and exhaust pushrods are different lengths, then two adjustable pushrods are required and the same process repeated. The adjustable pushrod trick is valid for fixed-pivot shaft-type rocker arm engines as well as for engines with ball-type rocker arms.

For the most part, the rocker arm tip radius on stock-type rockers is best left alone. About all that can be done is to be certain the rocker tip radius is smooth and polished. Unless the proper equipment is available, this must be a "freehand" operation and is most easily done with Craytex abrasive sticks. Care must be taken not to "flatspot" the radius and also to be certain that in the plane perpendicular to the radius, the rocker arm tip is flat and not "cocked" off at an angle.

Valve stem tips must usually be rehardened if more than about .030 inch is removed in the process of correcting valve stem tip length. This is quickly and easily done, assuming the valves are of conventional materials and not stainless steel or other austenitic (non-heattreatable) alloys. Simply heat the valve stem tip with a welding torch until the tip color is a fairly bright red, then quench the stem in water. The trick is to use a fairly large welding torch tip and point the flame directly onto the valve stem tip. This will heat the tip quickly, and it must be quenched quickly because the tip surface only is to be hardened. If the red color extends more than about 1/8 inch from the valve stem tip, the valve can be considered junk because heat penetration will cause hardening of the valve stem in the area of the valve lock groove, which must be avoided at all costs to prevent valve breakage at this point. After hardening, the valve stem and the tip must be cleaned and polished with crocus cloth to remove any scale and also to improve the surface finish of the valve stem tip.

There are two alternatives to hardening the valve stem tips. One, the valve stem tips can be hard-faced with Stellite, a very hard and tough alloy, but this is best left to someone experienced in hard-facing techniques. Two, valve lash caps can be used between the valve stem tips and the rocker arm tips. These are inverted cups that fit over the valve stem tips and are very hard and tough. The valve lash caps must usually be quite shallow in order to avoid contact with the valve locks and the spring retainers.

If either alternative is used, the thickness of the finished hard facing or the thickness of the valve lash caps must be taken into consideration from the outset so that the rocker arm geometry will be correct when all pieces are assembled.

The foregoing description suggests that when rocker arm geometry is being observed, the valve lash should be zero or very close to it. The reason, particularly with ball type rocker arms, is that zero valve lash will prevent the rocker arm from "cocking" to the side as the valve is opened and closed, which in turn will prevent false observations. This method will result in a pushrod length that is very slightly shorter than that actually required. However, if it seems necessary to make an error in pushrod length, it is far better to make the error in favor of a shorter pushrod by a lot than a longer pushrod by a little.

The only engines that are exempt from rocker geometry problems are those in which rocker arms are not used. Therefore, overhead camshaft engines using rocker arms are subject to the same rocker arm geometry problems as those previously discussed, even though pushrods are not present in such engines.

In some of these engines in which the rocker arm pivot point is between the cam lobe and the valve stem, as in the single overhead camshaft 427 Ford V8, rocker arm geometry discrepancies are corrected by valve stem length and/or rocker stand height changes. Inasmuch as this has been outlined and the same corrective measures apply, it can be dismissed without further comment.

In overhead camshaft engines where the cam lobe contacts the rocker arm between the rocker arm pivot point and the valve stem, as exemplified by current Datsun single overhead camshaft four and six cylinder engines, rocker arm geometry can and does become almost unbelievably critical. The first rule of equalizing valve stem length must be followed in such cases, but the allowable valve stem length variations should be tightened to almost zero. Finished valve stem length is the important item in these engines because it has the most direct influence upon rocker arm geometry.

Most engines of this type use a rocker arm with a radiused pad that contacts the cam lobe, and the manner in which the cam lobe contacts the radiused pad is very nearly as important as rocker arm geometry itself, and the two factors are inseparably related. In fact, when the cam lobe-rocker pad contact condition is right, the rocker arm geometry will also be right. Problems occur if the cam lobe base circle is changed, larger or smaller than stock, or if the valve lift has been changed in either direction from stock with a cam lobe base circle that is the same or larger or smaller than stock. Therefore, any deviation from a camshaft of stock dimensions will not only change the rocker arm geometry but will also change the cam lobe-rocker pad contact condition.

This condition can be observed and corrected by the following methods: Assuming all valve stem lengths have been equalized, place a light inner valve spring or fuel pump spring on a valve with the retainer and valve locks. Make sure that both the cam lobe and the rocker arm pad are clean and dry, then spread a very light coat of Prussian blue paste on the nose of the cam lobe and down each flank of the lobe. With the nose of the cam lobe turned away from the rocker arm pad, install the rocker arm and set the valve lash to the proper figure. Rotate the camshaft slowly by hand one full revolution. Very carefully observe the traces of Prussian blue paste that have been transferred from the cam lobe to the rocker arm pad. Ideally, the cam lobe contact patch should be exactly centered on the rocker arm pad. If the contact patch is closer to one end or the other of the rocker arm pad, then corrections are absolutely essential. At no time can the cam lobe extend beyond either or both ends of the rocker arm pad. This will chew off the cam lobe in less time than it takes to tell the tale.

If the cam lobe contact patch on the rocker arm pad is closer to the point of the rocker arm than it is to the valve stem end of the rocker, the valve stems must be lengthened. If the opposite is true, that is, if the cam lobe contact patch is closer to the valve stem end of the rocker, the valve stems must be shortened. However, the effective length of the valve stems must normally be made longer.

Depending upon layout, this can be accomplished by either adding a hard-facing material of the correct finished thickness to the valve stem tips or by the use of valve lash caps, as previously described. The Datsun engines require a special valve lash pad that is slotted to accept and guide the rocker arm tip, and the outside diameter of the pad must fit inside the valve spring retainer properly.

As a starting point, the amount the effective valve stem length must be increased is the difference between the stock cam lobe base radius and the cam lobe base radius of the camshaft being installed, multiplied by the rocker arm ratio. As an example, assume the base circle of the stock cam lobe is 1.300 inches. Half this dimension is the base radius, .650 inch. If the base circle of the cam lobe is reduced to 1.100 inches, then the base radius is reduced to .550 inch, which is .100 inch smaller. If the rocker arm ratio is 1.5 to 1, the .100 inch difference in base radius must be multiplied by 1.5, which is equal to .150 inch, and is the amount the effective valve stem length must be increased. This method will usually be quite close, but final determination of effective valve stem length must be made by a very close visual examination of the cam lobe contact patch on the rocker arm pad. If there is a direction to lean with the thought of improving matters over and above stock, then the proper direction is toward a very slightly longer valve stem length than that actually required, and then by no more than about .010 inch.

With this type of overhead camshaft layout, any and all changes in the valve train become a function of rocker arm ratio. Consequently, dimensional tolerances and changes become much more critical, affecting not only rocker arm geometry and cam lobe patch location, but actual, measured rocker arm ratio as well.

This lengthy and detailed discussion will hopefully serve to emphasize the extreme importance of correct rocker arm geometry in any engine of any performance level. The results obtained are certainly worth all the time and effort involved to make it right. Fortunately, when the job is done correctly, all valve train components will usually last the life of the rest of the engine assembly, and more. Nevertheless, if special valve lengths or special pushrod lengths are required, it's a good plan to have a few spares on hand in the event of other unforeseen disasters.
Posted By: Thumperdart

Re: What is Proper Rocker Arm Geometry? - 10/14/14 07:29 PM

Quote:

Quote:

my question is why even worry about it? I have never checked nor really give a flip if they are off a little. unless you are doing something very specific or searching for every bit of HP you can get what does it matter? there are thousands of motors built and last for a long period of time with no problems.


Thousands of motors out there running as well that never have the clearances checked either...........do you advocate that as well?

Are we building motors RIGHT......or are we just throwing them together and hoping for the best.........or are we just doing something in between.

Right is right.....half azz is half azz

Monte




Couldn`t agree more...............
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/14/14 08:15 PM

Quote:

Has this been corroborated on a dyno, as in you KNOW you make less power or is the car just running a little slower ET.............Where on the track did it slow? Is it early, in the middle or on the top end. If the car runs the same speed it ran before, it makes the same power. You just may not be getting it down as consistently or as easily as you were before.

My point is that it seems hard for me to believe that MORE revs and better stability has cost you power

Monte




Monte,

The car slowed across the board, from 60' out the car was slower. The trap RPM and MPH were down as well.

The reason for this loss of performance in my opinion is this...

Valvetrain Geometry affects net lift at the valve as well as effective duration.

This is what is missing from many discussions regarding valvetrain geometry.
Posted By: BradH

Re: What is Proper Valvetrain Geometry? - 10/14/14 08:34 PM

Yes, any change to the valve train geometry will result in some associated change to the effective valve lift curve. Nothing new here, but it takes some seriously anal types like myself who will admit to having actually measured the entire lift curve as the result of making some changes to the geometry.

I've done the same thing to see what the net change to the lift curve is from different rocker arm brands & ratios, as well as lash changes for solid cams.

You still haven't provided the track test conditions (temp, humidity, barometric pressure, etc.) for the before & after comparisons, along w/ the actual incremental differences in ET & MPH.
Posted By: clonestocker

Re: What is Proper Valvetrain Geometry? - 10/14/14 09:19 PM

Trent,

A few weeks back I was at the track and it was slow. The water grains were high I was told. Care to post the difference on the time slip. If your car fell off everywhere the DA and Humidity could have knocked your #'s down.
Posted By: Hemi Allstate

Re: What is Proper Valvetrain Geometry? - 10/14/14 09:37 PM


You can check the DA here.

http://www.dragtimes.com/da-density-altitude-calculator.php

Mark
Posted By: Quicktree

Re: What is Proper Rocker Arm Geometry? - 10/14/14 10:29 PM

Quote:

Quote:

my question is why even worry about it? I have never checked nor really give a flip if they are off a little. unless you are doing something very specific or searching for every bit of HP you can get what does it matter? there are thousands of motors built and last for a long period of time with no problems.


Thousands of motors out there running as well that never have the clearances checked either...........do you advocate that as well?

Are we building motors RIGHT......or are we just throwing them together and hoping for the best.........or are we just doing something in between.

Right is right.....half azz is half azz

Monte


call it what ever you want, mine seem to run prrety dang good and last for quite a while so I could care less.
Posted By: Monte_Smith

Re: What is Proper Rocker Arm Geometry? - 10/14/14 10:50 PM

Quote:

Quote:

Quote:

my question is why even worry about it? I have never checked nor really give a flip if they are off a little. unless you are doing something very specific or searching for every bit of HP you can get what does it matter? there are thousands of motors built and last for a long period of time with no problems.


Thousands of motors out there running as well that never have the clearances checked either...........do you advocate that as well?

Are we building motors RIGHT......or are we just throwing them together and hoping for the best.........or are we just doing something in between.

Right is right.....half azz is half azz

Monte


call it what ever you want, mine seem to run prrety dang good and last for quite a while so I could care less.


Well carry on then......but no reason to tell everyone else it doesn't matter and they shouldn't care.

Monte
Posted By: Quicktree

Re: What is Proper Rocker Arm Geometry? - 10/14/14 11:35 PM

Quote:

Quote:

Quote:

Quote:

my question is why even worry about it? I have never checked nor really give a flip if they are off a little. unless you are doing something very specific or searching for every bit of HP you can get what does it matter? there are thousands of motors built and last for a long period of time with no problems.


Thousands of motors out there running as well that never have the clearances checked either...........do you advocate that as well?

Are we building motors RIGHT......or are we just throwing them together and hoping for the best.........or are we just doing something in between.

Right is right.....half azz is half azz

Monte


call it what ever you want, mine seem to run prrety dang good and last for quite a while so I could care less.


Well carry on then......but no reason to tell everyone else it doesn't matter and they shouldn't care.

Monte


i didn't tell anyone anything, look again i asked why. like I said it makes zero difference to me and most bracket racers. I could care lees if it's a .1 slower. it's obvious it has no bearing on longevity and I don't know very many bracket or index racers that bother with trying to find out if it's off or not. it's a pretty much given they are off.
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/15/14 12:43 AM

I ran the car Saturday utilizing the "mid lift theory". I swapped back to my previous setup Saturday night with the intentions of testing again on Sunday. Unfortunately, I was sick on Sunday morning and was unable to return to the track.

I concluded the performance loss from the other 100+ runs I have made with the car in similar conditions. Not ideal, but it is what is. I can go more in depth with weather specifics from comparative runs if need be.

Regardless, loss of the effectiveness of a camshaft seems like a notable flaw that is very rarely mentioned. I personally will not be sweeping it under the rug. As such, I guess I was looking for opinions regarding the subject and how to find a middle ground. The more I research this subject though the more I think its either a big guarded secret or the majority are just plain happy not knowing.

Since I think it's to late for me to go back to the latter of the two groups, if anyone has any input regarding optimal valvetrain geometry which also effectively utilizes the camshaft I certainly look forward to your input.
Posted By: TRENDZ

Re: What is Proper Valvetrain Geometry? - 10/15/14 02:17 AM

Quote:

Quote:

Has this been corroborated on a dyno, as in you KNOW you make less power or is the car just running a little slower ET.............Where on the track did it slow? Is it early, in the middle or on the top end. If the car runs the same speed it ran before, it makes the same power. You just may not be getting it down as consistently or as easily as you were before.

My point is that it seems hard for me to believe that MORE revs and better stability has cost you power

Monte




Monte,

The car slowed across the board, from 60' out the car was slower. The trap RPM and MPH were down as well.

The reason for this loss of performance in my opinion is this...

Valvetrain Geometry affects net lift at the valve as well as effective duration.


rocker geometry/pushrod length will change SPEED, stability, and lift at the valve, but not duration.(given the same lash settings)
You can "play" with fulcrum points to speed up or slow down off the seat velocity. You may have accidentally set up the engine originally with this "trick". You may have been using the engine in the range that the effects worked... and that's great. But now you've traded some of that speed for durability. You pay the toll on either side of the fence.
Posted By: HotRodDave

Re: What is Proper Valvetrain Geometry? - 10/15/14 03:11 AM

There is no perfect rocker geometry for every situation. Maybe your valve train is stable enough you can change valve lift velocities to take advantage of head flow, if you heads flow real good up high you may get more power setting it up to get max velocity at peak valve lift and get a tiny extra lift but you can't do that if your valve train can't handle some weird harmonics you introduced. Maybe you heads flow real good at low lift, you may gain some power by setting the rockers to yank the valve off the seat faster, course it don't help if your valve starts bouncing because you close it too fast. You just got to experiment and figure out what works best on your combo.

For most guys getting the roller center/shaft center/ PR pivot 90* at 1/2 lift will be close enough, for the last 1% of guys they need to do some experimenting on either side of that.

Some times you want a RPM intake for best performance but sometimes you need the Super victor
Posted By: dvw

Re: What is Proper Valvetrain Geometry? - 10/15/14 03:34 AM

Quote:

Quote:

Has this been corroborated on a dyno, as in you KNOW you make less power or is the car just running a little slower ET.............Where on the track did it slow? Is it early, in the middle or on the top end. If the car runs the same speed it ran before, it makes the same power. You just may not be getting it down as consistently or as easily as you were before.

My point is that it seems hard for me to believe that MORE revs and better stability has cost you power

Monte




Monte,

The car slowed across the board, from 60' out the car was slower. The trap RPM and MPH were down as well.

The reason for this loss of performance in my opinion is this...

Valvetrain Geometry affects net lift at the valve as well as effective duration.

This is what is missing from many discussions regarding valvetrain geometry.



So by running less than optimal geometry you may have increased lift. If the performance loss wasn't due to conditions I would suggest you have the wrong cam. Why run the wrong geometry to increase lift and sacrifice stability and rpm range? Swaping a cam with proper duration, lift, LCA, and centerline would be a gain all around.
Doug
Posted By: 451Mopar

Re: What is Proper Valvetrain Geometry? - 10/15/14 05:12 PM

Tag to read later when I have more time.
Different valve lengths will change the contact point and geometry quite a bit.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/15/14 05:32 PM

I am surprised the geometry guru that popped up a few months ago hasn't jumped on this
Posted By: Thumperdart

Re: What is Proper Valvetrain Geometry? - 10/15/14 06:29 PM

Quote:

I am surprised the geometry guru that popped up a few months ago hasn't jumped on this





Maybe he`s sick of the "Experts" tellin him he`s crazy and doesn`t know what he`s talking about............
Posted By: BradH

Re: What is Proper Valvetrain Geometry? - 10/15/14 06:32 PM

Quote:

I concluded the performance loss from the other 100+ runs I have made with the car in similar conditions. Not ideal, but it is what is. I can go more in depth with weather specifics from comparative runs if need be.



It would help to know how much of a performance loss you've seen and how much could be attributed to the changing atmospheric conditions. I've seen some pretty noticeable gains & losses due to that myself.
Quote:

... if anyone has any input regarding optimal valvetrain geometry which also effectively utilizes the camshaft I certainly look forward to your input.



My ... you probably have improved the valve train dynamics while reducing how aggressive the engine "saw" the cam. Now that you've addressed one potential issue, you can look into running different lobes to see about a performance improvement.

That's why you've got roller lobes designed for endurance applications that don't beat the sh!t outta the valve train and ultra-aggressive lobes that are designed to kick the valves open for more torque, yet require more spring load / limited RPM capabilities / increased maintenance schedules.

Like others have said, it's always a trade off. I don't know what else can be said about this.
Posted By: RT540

Re: What is Proper Valvetrain Geometry? - 10/15/14 06:36 PM

No one has mentioned the low pivot geometry.

Jesel.com and in the Tech Tips FAQ have some insite in why they think this is important with high spring pressure.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/15/14 10:28 PM

Quote:

Quote:

I am surprised the geometry guru that popped up a few months ago hasn't jumped on this





Maybe he`s sick of the "Experts" tellin him he`s crazy and doesn`t know what he`s talking about............


you must have not been paying attention. no one told him that they were getting on his case because he was trying to pimp his product. nice try though.
Posted By: jamesc

Re: What is Proper Valvetrain Geometry? - 10/16/14 12:53 AM

i'm not going to say it doesn't matter because it does. personally i don't get my panties in a wad over it. i mock the valvetrain, roll it over and eyeball stuff. as long as nothing looks terribly amiss i run it.

i think this is one of those things people like to "discuss" but for most guys unless there's something terribly out of whack imho they should concentrate efforts elsewhere

i wouldn't put iron rockers on a prostock and i wouldn't put a dry sump on a 10 second bracket car
Posted By: AndyF

Re: What is Proper Valvetrain Geometry? - 10/16/14 12:57 AM

Low pivot is the way to go with high spring pressure. Mid-lift works well for moderate spring pressure.

The low pivot setup puts the rocker arm perpendicular to the valve at 2/3 lift rather than mid-lift. Consequently you have more scrub at low lift (low spring force) but less scrub at high lift (high spring force)

The old Chevy engine builder guide from 30 years ago recommended low pivot for high spring pressure but even though it has been around for a long time not too many people talk about. Most everyone recommends the mid-lift method including most of the cam company websites.

It takes a ton of work to do the low pivot method on a stock Mopar head. Relocating the shaft is a pain. Longer valves with shorter rocker arms is one way to skin the cat or mill off the pedastals and use Max Wedge style blocks for the shafts.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/16/14 12:25 PM

here is my theory, at my level it is not significant enough to make a big difference. if some of you think it is give us some facts. like HP difference and dyno info/ life of the motor etc. I haven't seen anyone offering anything but unproven opinion. and yes I do visually check contact points through the motion but I have never worried about if the geometry is off a little. I am sure at high levels it becomes more crucial.
Posted By: Crizila

Re: What is Proper Valvetrain Geometry? - 10/16/14 04:16 PM

Quote:

Low pivot is the way to go with high spring pressure. Mid-lift works well for moderate spring pressure.

The low pivot setup puts the rocker arm perpendicular to the valve at 2/3 lift rather than mid-lift. Consequently you have more scrub at low lift (low spring force) but less scrub at high lift (high spring force)

The old Chevy engine builder guide from 30 years ago recommended low pivot for high spring pressure but even though it has been around for a long time not too many people talk about. Most everyone recommends the mid-lift method including most of the cam company websites.

It takes a ton of work to do the low pivot method on a stock Mopar head. Relocating the shaft is a pain. Longer valves with shorter rocker arms is one way to skin the cat or mill off the pedastals and use Max Wedge style blocks for the shafts.


Pretty sue the factory small block Chevy engines were and are set up using the 2/3 lift method. My brother recently purchased a Chevy 350 crate motor that was set up that way. I'm sure it is all about longevity on a factory stock motor.
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/16/14 04:18 PM

Quote:

here is my theory, at my level it is not significant enough to make a big difference. if some of you think it is give us some facts. like HP difference and dyno info/ life of the motor etc. I haven't seen anyone offering anything but unproven opinion. and yes I do visually check contact points through the motion but I have never worried about if the geometry is off a little. I am sure at high levels it becomes more crucial.




Just curious, in your opinion is .025 net lift loss significant? I ask because that's what I've lost by changing my geometry.

I also gain and or lose over 400 useable RPM in my shift points by changing the geometry.

Still not to worry about?
Posted By: Crizila

Re: What is Proper Valvetrain Geometry? - 10/16/14 04:27 PM

Quote:

Quote:

here is my theory, at my level it is not significant enough to make a big difference. if some of you think it is give us some facts. like HP difference and dyno info/ life of the motor etc. I haven't seen anyone offering anything but unproven opinion. and yes I do visually check contact points through the motion but I have never worried about if the geometry is off a little. I am sure at high levels it becomes more crucial.




Just curious, in your opinion is .025 net lift loss significant? I ask because that's what I've lost by changing my geometry.

I also gain and or lose over 400 useable RPM in my shift points by changing the geometry.

Still not to worry about?


Keep in mind, you will loose .025 - .030 lift ( based on the cam specs ) on a sm blk just because of the push rod angle. Sorry, didn't mean to jump in.

Attached picture 8302072-valveliftmeasure.jpg
Posted By: Thumperdart

Re: What is Proper Valvetrain Geometry? - 10/16/14 04:40 PM

What about p-rod deflection? George Koople and myself just for giggles mocked up my rpm`s to achieve optimum geometry and we would of had to raise my shafts WAY up to get it right based on my valve lengths and rockers or cut the stands and go from there. When I ran smallblocks, the sweep sucked on the different rockers I tried and usually started outboard towards the ex. and got worse at mid and full lifts and wore out the guides fairly quickly in my 11-second daily driver. The BB`s however are WAY better in terms of mid and full lifts although not perfect and the p-rod angles are great. The best I ever saw was at Pettis on a BB Chubby and Jesel rockers...........damn near perfect.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/16/14 05:18 PM

Quote:

Quote:

here is my theory, at my level it is not significant enough to make a big difference. if some of you think it is give us some facts. like HP difference and dyno info/ life of the motor etc. I haven't seen anyone offering anything but unproven opinion. and yes I do visually check contact points through the motion but I have never worried about if the geometry is off a little. I am sure at high levels it becomes more crucial.




Just curious, in your opinion is .025 net lift loss significant? I ask because that's what I've lost by changing my geometry.

I also gain and or lose over 400 useable RPM in my shift points by changing the geometry.

Still not to worry about?


no because I am not worried about a few HP, like I said I am a bracket racer and as long is it doesn't have a reliability issue I could care less. tell me how much power you lost?
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/16/14 05:33 PM

Quote:

Quote:

Quote:

here is my theory, at my level it is not significant enough to make a big difference. if some of you think it is give us some facts. like HP difference and dyno info/ life of the motor etc. I haven't seen anyone offering anything but unproven opinion. and yes I do visually check contact points through the motion but I have never worried about if the geometry is off a little. I am sure at high levels it becomes more crucial.




Just curious, in your opinion is .025 net lift loss significant? I ask because that's what I've lost by changing my geometry.

I also gain and or lose over 400 useable RPM in my shift points by changing the geometry.

Still not to worry about?


no because I am not worried about a few HP, like I said I am a bracket racer and as long is it doesn't have a reliability issue I could care less. tell me how much power you lost?




Sounds like you already know how much I lost, a few HP.

So we agree it makes a difference?
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/16/14 05:36 PM

Quote:

Quote:

Quote:

Quote:

here is my theory, at my level it is not significant enough to make a big difference. if some of you think it is give us some facts. like HP difference and dyno info/ life of the motor etc. I haven't seen anyone offering anything but unproven opinion. and yes I do visually check contact points through the motion but I have never worried about if the geometry is off a little. I am sure at high levels it becomes more crucial.




Just curious, in your opinion is .025 net lift loss significant? I ask because that's what I've lost by changing my geometry.

I also gain and or lose over 400 useable RPM in my shift points by changing the geometry.

Still not to worry about?


no because I am not worried about a few HP, like I said I am a bracket racer and as long is it doesn't have a reliability issue I could care less. tell me how much power you lost?




Sounds like you already know how much I lost.

So we agree it makes a difference?


I don't think so because i don't think you can tell me exactly?
Posted By: Thumperdart

Re: What is Proper Valvetrain Geometry? - 10/16/14 05:36 PM

Quote:

Quote:

Quote:

Quote:

... I have by definition established this previously stated "Optimal Geometry" in my application and as such I have now sacrificed performance to a degree...



Care to explain more re: this statement?




Utilizing the 90 degree mid lift theory in my application has resulted in increased valvetrain stability. It has also caused a loss of performance. It will now rev higher without adverse effects, but E.T has slowed regardless of shift point. Power has been sacrificed for stability.


Has this been corroborated on a dyno, as in you KNOW you make less power or is the car just running a little slower ET.............Where on the track did it slow? Is it early, in the middle or on the top end. If the car runs the same speed it ran before, it makes the same power. You just may not be getting it down as consistently or as easily as you were before.

My point is that it seems hard for me to believe that MORE revs and better stability has cost you power

Monte




Exactly what I was thinking. The track/street has too many variables to make an accurate assesement.
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/16/14 05:52 PM

"a few HP", those were your words. I thought maybe you had some hard facts from experience you were throwing out there since that's what your looking for from everyone else.

For what it's worth, I will state that without a doubt Valvetrain Geometry does affect engine performance characteristics.

To what extent is relative to each individual build... Your results may vary.
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/16/14 06:03 PM

Thumper, I agree there are other variables to consider. I plan on performing additional testing to reduce the amount of these variables and as such provide more solid information.

I typically measure success by E.T., others may use engine longevity or chase a dyno sheet.

I post questions on this forum to learn. I can usually weed through the posts and find something beneficial to my application. Not all information applies to everyone.

I will try to provide more information in the near future so that hopefully individuals can benefit from my experience just as I have from others.
Posted By: Thumperdart

Re: What is Proper Valvetrain Geometry? - 10/16/14 06:08 PM

I hear ya man. I use the track as a means to see if my mods/tune has hp benefits which result in lower et`s...........SOMETIMES! I`ll say this which may apply to your results; If the scrub is as bad as some I`ve seen, it can and will cock the valve which in turn COULD create more friction and let oil into the combustion chamber and oil doesn`t ignite well.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/16/14 10:27 PM

Quote:

"a few HP", those were your words. I thought maybe you had some hard facts from experience you were throwing out there since that's what your looking for from everyone else.

For what it's worth, I will state that without a doubt Valvetrain Geometry does affect engine performance characteristics.

To what extent is relative to each individual build... Your results may vary.


I thought I was pretty clear, I don't check it and don't worry about it. I have no idea how much difference in HP thats why asked for info from people who have fact/dyno data. im curious to know.
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/16/14 11:22 PM

Quote:

Quote:

"a few HP", those were your words. I thought maybe you had some hard facts from experience you were throwing out there since that's what your looking for from everyone else.

For what it's worth, I will state that without a doubt Valvetrain Geometry does affect engine performance characteristics.

To what extent is relative to each individual build... Your results may vary.


I thought I was pretty clear, I don't check it and don't worry about it. I have no iea how much difference in HP thats why asked for info from people who have fact/dyno data. im curious to know.



Well, I was going to ask permission to post, but I had to post to ask, so I'm just going to pee away on yet another geometry thread. Geometry makes a difference! Before valve side correction.

Attached picture 8302474-1413494539330.jpg
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/16/14 11:26 PM

After correction.

Attached picture 8302480-1413494780988.jpg
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/16/14 11:27 PM

Before and after graph.

Attached picture 8302482-1413494870803.jpg
Posted By: jamesc

Re: What is Proper Valvetrain Geometry? - 10/16/14 11:46 PM

so what we're talking here is less than a 1% difference?
thanks but i'll concentrate my efforts elsewhere
long as it's not damaging parts i'm ok with it
if i should ever decide to run comp eliminator maybe i'll revisit that position
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:02 AM

Quote:

so what we're talking here is less than a 1% difference?
thanks but i'll concentrate my efforts elsewhere
long as it's not damaging parts i'm ok with it
if i should ever decide to run comp eliminator maybe i'll revisit that position


lol yea thats really worth the effort
Posted By: HotRodDave

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:02 AM

Got any before after set up info? Mid lift, 2/3rds lift? Where did the 90* occur in the lift before correction?
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:03 AM

Quote:

Before and after graph.


pretty much what I thought, thanks for posting
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:39 AM

Quote:

so what we're talking here is less than a 1% difference?
thanks but i'll concentrate my efforts elsewhere
long as it's not damaging parts i'm ok with it
if i should ever decide to run comp eliminator maybe i'll revisit that position


46 horsepower at the 5800 shift point is a bit more than one percent. If you are referring to peak power, that isn't where you shift the motor.
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:41 AM

Quote:

Quote:

so what we're talking here is less than a 1% difference?
thanks but i'll concentrate my efforts elsewhere
long as it's not damaging parts i'm ok with it
if i should ever decide to run comp eliminator maybe i'll revisit that position


lol yea thats really worth the effort


yeah, I thought a couple tenths was worth it too.
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:44 AM

Quote:

Got any before after set up info? Mid lift, 2/3rds lift? Where did the 90* occur in the lift before correction?


What I can tell you is, the shaft had to be raised .270" to get to 90*.
Posted By: Chris'sBarracuda

Re: What is Proper Valvetrain Geometry? - 10/17/14 12:45 AM

Quote:

Quote:

Quote:

so what we're talking here is less than a 1% difference?
thanks but i'll concentrate my efforts elsewhere
long as it's not damaging parts i'm ok with it
if i should ever decide to run comp eliminator maybe i'll revisit that position


lol yea thats really worth the effort


yeah, I thought a couple tenths was worth it too.








There's NO WAY that's a couple tenths.. Total BS..


Chris..
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 01:15 AM

i'll bet correcting my geometry will not net anywhere near 46hp with my current combo. that would put me near 700hp with a small flat tappet cam.
Posted By: Monte_Smith

Re: What is Proper Valvetrain Geometry? - 10/17/14 03:27 AM

Quote:

i'll bet correcting my geometry will not net anywhere near 46hp with my current combo. that would put me near 700hp with a small flat tappet cam.


If it helps you 2 hp and only costs a little time it is worth it. Free power is free power.

This can go right along with "nah, I don't degree my cams, its probably close enough"........Im only bracket racing.................... and all those other things that are "close enough".

This is also the reason that stockers with cast intakes, thermo-quads, stock unported iron heads and various other things will embarrass most guys aluminum headed, big cam "race" motors on the track. Its called attention to detail and getting what you can out of a combo.

Monte
Posted By: pittsburghracer

Re: What is Proper Valvetrain Geometry? - 10/17/14 03:34 AM

I think if you are going to compare dyno tests the operating temps should be the same. They weren't in these tests on the results you have posted.
Posted By: Sport440

Re: What is Proper Valvetrain Geometry? - 10/17/14 03:35 AM

Quote:

Quote:

Got any before after set up info? Mid lift, 2/3rds lift? Where did the 90* occur in the lift before correction?


What I can tell you is, the shaft had to be raised .270" to get to 90*.




Raised to get to 90* at zero lift?? I think that's what "your" shooting for. I don't think that's best, if its what your doing.

Also there is more to the valvetrain geometry then the angle of the rocker to the valve.

Pushrod length and pushrod adjuster plays a big part too.

Like others of stated, there is no one Perfect valvetrain geometry. It can be manipulated to benefit the cam/spring/rocker combo.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 08:11 AM

Quote:

Quote:

i'll bet correcting my geometry will not net anywhere near 46hp with my current combo. that would put me near 700hp with a small flat tappet cam.


If it helps you 2 hp and only costs a little time it is worth it. Free power is free power.

This can go right along with "nah, I don't degree my cams, its probably close enough"........Im only bracket racing.................... and all those other things that are "close enough".

This is also the reason that stockers with cast intakes, thermo-quads, stock unported iron heads and various other things will embarrass most guys aluminum headed, big cam "race" motors on the track. Its called attention to detail and getting what you can out of a combo.

Monte


so how much does a builder charge to check and correct? by the way I am going down to buy a jeep from AAron down in Tampa tonight. he said he knows you.
Posted By: GTS340

Re: What is Proper Valvetrain Geometry? - 10/17/14 02:03 PM

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 02:54 PM

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok if a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 02:57 PM

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok its a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/17/14 03:15 PM

Quote:

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok its a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring


You know what I don't care about? It's you not caring. Listen, if you want drama, watch a soap opera. If you are truly interested in participating for the betterment of all, by all means, do so. Otherwise, step aside son, and let the grownups have a meaningful discussion.
Posted By: BradH

Re: What is Proper Valvetrain Geometry? - 10/17/14 04:15 PM

^^^

Countdown before this thread completely goes into the cyber-toilet: 3... 2... 1...
Posted By: Thumperdart

Re: What is Proper Valvetrain Geometry? - 10/17/14 04:28 PM

Quote:

Quote:

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok its a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring


You know what I don't care about? It's you not caring. Listen, if you want drama, watch a soap opera. If you are truly interested in participating for the betterment of all, by all means, do so. Otherwise, step aside son, and let the grownups have a meaningful discussion.





MY HERO................
Posted By: Crizila

Re: What is Proper Valvetrain Geometry? - 10/17/14 05:02 PM

Quote:

What is Proper Rocker Arm Geometry? I used to believe you could buy a set of rocker arms, throw pushrods in and call it a day. This would be incorrect, or so it now seems... I am curious to know the following.

1.) What do you guys consider to be proper rocker arm geometry and why?

2.) What brand and/or style Rocker Arm do you recommend be utilized to achieve proper rocker geometry and why?


How much air should I run in my tires? - about the same generalization as the posters question. Think this thread went exactly where he thought it would. The OP runs at the same 2 tracks that I do. They are generally overwhelmed with cars. You are lucky if you can get 3 runs in - in a 6 hour period - after 3 oildowns and a 2000 ft DA change. Gleaning any useable info ( within in 2 tenths and 5 MPH ) is living in fantasy land. I declare this thread closed!! Is it winter yet??
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 05:26 PM

Quote:

Quote:

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok its a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring


You know what I don't care about? It's you not caring. Listen, if you want drama, watch a soap opera. If you are truly interested in participating for the betterment of all, by all means, do so. Otherwise, step aside son, and let the grownups have a meaningful discussion.


you know what I care about your opinion? don't ask heck I don't even know who you are..
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 05:27 PM

Quote:

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok if a builder can guarantee me 46 horsepower for a few hundred bucks I am in if not I'm back to not caring


stupid auto correct on my phone
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 05:35 PM

Quote:

Quote:

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok its a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring


You know what I don't care about? It's you not caring. Listen, if you want drama, watch a soap opera. If you are truly interested in participating for the betterment of all, by all means, do so. Otherwise, step aside son, and let the grownups have a meaningful discussion.


ok i looked at your profile, so you are a engine builder. where are you located? i'll be glad to pay you for 46 additional guaranteed HP. how much? I call BS on this one
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 05:42 PM

Quote:

Quote:

Quote:

Quote:

Depends how bad it is, if you have to flat mill shaft saddles and make blocks to change shaft height and/or offset the shaft it will be considerably more expensive than just checking it. Plus you may need new pushrods if moved much.


ok its a builder can guarantee me 46 horsepower for a few hundred bucks a min if not I'm back to not caring


You know what I don't care about? It's you not caring. Listen, if you want drama, watch a soap opera. If you are truly interested in participating for the betterment of all, by all means, do so. Otherwise, step aside son, and let the grownups have a meaningful discussion.





MY HERO................


coming from a drama queen
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/17/14 07:30 PM

Quote:

Quote:

What is Proper Rocker Arm Geometry? I used to believe you could buy a set of rocker arms, throw pushrods in and call it a day. This would be incorrect, or so it now seems... I am curious to know the following.

1.) What do you guys consider to be proper rocker arm geometry and why?

2.) What brand and/or style Rocker Arm do you recommend be utilized to achieve proper rocker geometry and why?


How much air should I run in my tires? - about the same generalization as the posters question. Think this thread went exactly where he thought it would. The OP runs at the same 2 tracks that I do. They are generally overwhelmed with cars. You are lucky if you can get 3 runs in - in a 6 hour period - after 3 oildowns and a 2000 ft DA change. Gleaning any useable info ( within in 2 tenths and 5 MPH ) is living in fantasy land. I declare this thread closed!! Is it winter yet??




Regarding my first question, 90* at mid lift is not the same as 90* at 2/3 lift, nor is it the same as 90* at full lift. All three are different, all three require a different amount of modification to achieve and all three will provide different results. I was curious to know which method was preferred and why. Seems like a reasonable question.

As for the second question, ductile iron rockers are not the same as roller rockers and each individual manufacturer of roller rockers is said to provide variables. The lengths are said to vary, as such the geometry will vary as well. It has been said many times, "don't buy the cheap roller rockers, buy the high dollar ones instead". I thought maybe someone could come forward with specifics relative to geometry to justify that claim. I now believe that either the majority of people don't know the difference or alternatively aren't speaking up, for varying reasons of course...

Furthermore, who said anything about having to pay a machine shop to set up there valvetrain? If you have common sense and basic tools, it will get you a long way. If you have common sense and no tools I would think you would at least like to know what your paying the machine shop for. If you have no tools and no common sense, I hope you don't take your parts to the guy you were trashing on the internet...

And yes, this thread did go about how I expected. How nice...

With that being said, Thanks to anyone who has or continues to offer constructive input. I do weed through the discussion for it and as always, I greatly appreciate it.
Posted By: Crizila

Re: What is Proper Valvetrain Geometry? - 10/17/14 08:11 PM

Here is some constructive input. There is no correct answer to your question - "what is proper rocker arm geometry" - which, as you said, you already knew. Just as there is no correct answer to "what is the best rocker arm". There also is no correct answer to what is the MOST correct rocker arm geometry. Hope this helps. Here is a tip for you; shoot for longevity. It might not give you the most area under the curve, but it will cost the least and give you the highest probability of getting to the end of the track - on a regular basis. JMO. So, how much air should I put in my tires??

Attached picture 8303434-mypitgal.jpg
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/17/14 10:15 PM

if you are talking too me I have no desire to spend my time messing with rocker are geometry, I would rather pay to have it done if someone can guarantee me 46HP for a minimum charge. fact is I am betting it can't be done. I have no hard feeling against this builder that claims he gained 46HP correcting the geometry I just don't believe it. for someone I do not know or never heard of I would have to be standing there watching. now if Monte, Best machine Comp Wedge or BG came on here and told me that I may be more likely to believe. when you make a post your not going to get everyone telling you what you want to hear,thats just the way it is. sure I would like to see more info, still no one has said it causes problems just a loss of a little power, how much who knows
Posted By: BradH

Re: What is Proper Valvetrain Geometry? - 10/17/14 10:23 PM

Yawn...

Attached picture 8303552-bored-now.jpg
Posted By: Crizila

Re: What is Proper Valvetrain Geometry? - 10/18/14 12:21 AM

Quote:

Yawn...




Attached picture 8303655-cattalk.jpg
Posted By: cudaman1969

Re: What is Proper Valvetrain Geometry? - 10/18/14 12:45 AM

I'm still trying to figger out what 50% at 90* means, explain please.
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/18/14 02:12 AM

On a roller rocker, at 50% of net valve lift, the geometric line from the centerline of the rocker shaft to the centerline of the roller axle should be at 90* to the valve stem. Not the centerline of the shaft to the tip of the valve as some have stated, and as a shoe type rocker is measured.
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/18/14 02:19 AM

Oh, one more thing. The adjuster angle and pivot location should be 90* at 50% also, but is built into the rocker and is what it is. You work with what you have.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/18/14 02:39 AM

I have to ask, B3R3 are you the guy that was selling a rocker correction kit?
Posted By: Hemi Allstate

Re: What is Proper Valvetrain Geometry? - 10/18/14 03:09 AM

Here,

https://board.moparts.org/ubbthreads/show...e=1#Post7923218
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/18/14 03:12 AM

Quote:

Here,

https://board.moparts.org/ubbthreads/show...e=1#Post7923218


I thought so, case closed
Posted By: cudaman1969

Re: What is Proper Valvetrain Geometry? - 10/18/14 04:17 AM

Quote:

Oh, one more thing. The adjuster angle and pivot location should be 90* at 50% also, but is built into the rocker and is what it is. You work with what you have.



Thank you for the explantion, just trying to follow thru all the BS. Just got my first Hemi and would like to check out this process on the build up.
Posted By: polyspheric

Re: What is Proper Valvetrain Geometry? *DELETED* - 10/22/14 01:55 AM

Post deleted by polyspheric
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/22/14 02:15 AM

Quote:

The adjuster angle and pivot location should be 90* at 50% also, but is built into the rocker

It isn't, and you can't.




Can you expand on this?
Posted By: B3RE

Re: What is Proper Valvetrain Geometry? - 10/22/14 03:12 AM

Quote:

Quote:

The adjuster angle and pivot location should be 90* at 50% also, but is built into the rocker

It isn't, and you can't.




Can you expand on this?



Yes, I'm curious. Isn't what, and can't what?
Posted By: polyspheric

Re: What is Proper Valvetrain Geometry? *DELETED* - 10/22/14 03:33 PM

Post deleted by polyspheric
Posted By: MadMopars

Re: What is Proper Valvetrain Geometry? - 10/22/14 04:55 PM

I read the post. Jim Miller did it, it can be done. Regarding the patent and so on, I read that too.
Posted By: gregsdart

Re: What is Proper Valvetrain Geometry? - 10/23/14 01:53 AM

Quote:

Quote:

i'll bet correcting my geometry will not net anywhere near 46hp with my current combo. that would put me near 700hp with a small flat tappet cam.


If it helps you 2 hp and only costs a little time it is worth it. Free power is free power.

This can go right along with "nah, I don't degree my cams, its probably close enough"........Im only bracket racing.................... and all those other things that are "close enough".

This is also the reason that stockers with cast intakes, thermo-quads, stock unported iron heads and various other things will embarrass most guys aluminum headed, big cam "race" motors on the track. Its called attention to detail and getting what you can out of a combo.

Monte



Warren Johnson story

Observer, watching Warren test different belts to drive accessories.
"That is probably worth no more than a 1/4 hp, if at all"
Warren;
Maybe, but if I find one hundred things that produce a 1/4 hp, I have gained 25"
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/23/14 12:23 PM

Quote:

Quote:

Quote:

i'll bet correcting my geometry will not net anywhere near 46hp with my current combo. that would put me near 700hp with a small flat tappet cam.


If it helps you 2 hp and only costs a little time it is worth it. Free power is free power.

This can go right along with "nah, I don't degree my cams, its probably close enough"........Im only bracket racing.................... and all those other things that are "close enough".

This is also the reason that stockers with cast intakes, thermo-quads, stock unported iron heads and various other things will embarrass most guys aluminum headed, big cam "race" motors on the track. Its called attention to detail and getting what you can out of a combo.

Monte



Warren Johnson story

Observer, watching Warren test different belts to drive accessories.
"That is probably worth no more than a 1/4 hp, if at all"
Warren;
Maybe, but if I find one hundred things that produce a 1/4 hp, I have gained 25"


thats why stocker motors cost so much, thats why I bracket race.
Posted By: Quicktree

Re: What is Proper Valvetrain Geometry? - 10/23/14 12:26 PM

but my offer still stands, any builder that can guarantee 46hp by correcting geometry I am in. will chassis dyno the car before and after. and before and after track tests. .2 for a few hundred bucks will be the best bang for the buck ever spent.
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