Setting valve lash - how do you do it?

Hello,

Just curious what procedure fellow Mopar enthusiasts with mechanical cams use to set valve lash.

1) The last time I set valve lash on my Barracuda, I followed Hughes Engines' procedure:
http://www.hughesengines.com/Upload/productInstructions/ValveAdjust.pdf

2) Prior to that, I used the EOIC method. The EOIC procedure has you set the lash on the intake valve when the exhaust valve for the same cylinder begins to open (EO). The EOIC procedure has you set the lash on the exhaust valve when the intake valve for the same cylinder begins to close (IC). This is Comp Cams preferred method, as documented by their youTube video:
https://www.youtube.com/watch?v=3gMYWLMAzao

3) Next, I have heard guys setting lash on the intake and exhaust valves when the piston is on its way up the cylinder during the compression stroke and both intake and exhaust rockers are "loose".

Finally, I read this Drag Magazine article on setting valve lash:
http://www.dragzine.com/news/how-to-set-and-adjust-valve-lash-like-a-pro/
Near the end of the article the top engine builders provide their 7 tips for setting valve lash. I didn't understand tip 3 ("ignore chilton manual procedure") when the engine builders said to set lash in firing-order order. Is that the Hughes Engines procedure (1) or is that setting both intake and exhaust on the cylinder that is about to fire procedure (3)? The main thing I want to ensure is that the lifter is truly on the base circle of the camshaft when I set the lash. I fear using procedure (3) might result in setting lash on the intake or exhaust when the lifter is NOT on the base circle.


How do you set valve lash?

I use the Mopar Performance valve lash chart

My 440 with MP max wedge style iron rockers is happy with it so I am happy

I typically use your #2 posted above.
Having just degree'd the cam in on my 340 I was a little stunned how broad the base circle was.
After watching the dial indicator on the cam it didn't move at all for a long time.

I keep the intake off till I have em adjusted so all the hand turning wont scrape enough cam lube off of the lobes to fubar the breakin, maybe OCD but cam failures are epidemic so I go that extra mile. with the dampener slit at TDC (#6 firing with the dots left at 6/12 o'clock) & do #6 then hand turn the dampener 1/4 turn till the dist rotor is at the next cap terminal (or a strip of paper for a ruler on the dampener 5.694" if dist is still out) then do #5 & so on. For a IE .020" gap I get a slight drag on a .021" feeler gauge and no drag on a .019" feeler gauge then I (re) goop the lobes/install intake

For small street cams(under 240 degrees at .050) I set both at TDC on the firing stroke, all other cams I use the EOIC method I do set one side at a time cold and put the valve cover back on and then do the other side. I then redo them again after warming the motor up and breaking in the cam or on regular maintence checks on the Hi Po cams Good luck, let us know what you end up doing and your results

That is the Hughes Engines procedure (1).

Believe it or not GM used this procedure starting in 1957 on the solid lifter 283 motors, according to a lot of old time GM mechanics I don't and won't use that antiquated procedure

Why not?

EOIC

I have used this method since it was taught to me 40 years ago and have never had a problem

Try setting the valve lash this way and then recheck the lash with the EOIC method and see what you find on the lash differences Experience is the best teacher Let us know what your findings are

Once aqain, depends on the cam.

What Kunkel said reminded me of something I read that a cam over 280 (iirc?) advertized duration you'd wanna use the 8 position (MP) chart & with less than that you can get by with the 4 position method. Not sure if that has merit but wanted to toss it in. also I've adjusted the rockers then removed the rocker arm assy/pushrods and gooped the cam then replaced the assy as is. I dont believe a carefull R&R is going to change your lash adjustments.

My 440 cam is a Crower 294 duration 519 lift and seems happy with recommended .022 int. .024 ex. hot adjustment using MP chart.

I am always excited to learn a better way

I always used the EOIC method in the past with good results, however a friend of mine who runs a stocker showed me a faster way to set them still using the EOIC method but by going through the firing order. Start off by removing both valve covers then I did all the exhaust first 1-8-4-3-6-5-7-2 then the intakes 1-8-4-3-6-5-7-2. I was skeptical before i tried but after I couldn't believe how much faster I was able to go through the valves.

I think I may try something like that ... or just bring each cylinder in firing order to TDC and set both the intake and exhaust at the same time. As long as I am not on the downward stroke of the piston after TDC of the compression stroke (ie the power stroke), the exhaust valve will not begin to open. Both the intake and exhaust valves/lifters will be on the base circle a few degrees prior to TDC on the compression stroke.

The other factor is when I pull each plug and rotate the engine via the starter, it is very hard to bump it just right so as not to go past TDC on the compression stroke (or after the compression stroke in that case). If following that procedure, I really need to rotate the engine by hand. That is where the EOIC procedure has the advantage. You don't have to be as exact when bumping the engine via the starter.

Thank you everyone for the responses. I'm still learning.

Get yourself a good quality remote starter switch, hook it up to the starter relay and bump away. makes it much easier

Checked and then set my lash again. This time I used EOIC, starting on the driver's side engine bank with #7. I first checked to see where they all were to begin with. I had set the lash the last time using the old Mopar way. I had set int/exh to .016" lash cold. When I cycled through, they were all pretty close, some were a little loose (.018") but none were so far off that I thought there was a problem. The thing with setting lash is you tighten the lash adjuster until you feel a little drag when moving the feeler gauge between the valve tip and roller tip rocker. However, doing it that way still allows you to get a larger feeler gauge between the two (for example, .017" when setting the lash to .016"). So what is really the lash? A difference of .001" of an inch IS pretty ridiculously small. Maybe it doesn't matter.

This time through I set the lash to .012" int/exh cold using the EOIC method. Although I loose engine vacuum at idle with the tight lash, this engine makes more power with tight lash. It sounds better, too. I started on the driver's side bank of cylinders and did each valve for each cylinder before proceeding to the next cylinder. I like this method better because that way I don't get mixed up with which valves I did and which valves I didn't do.

When using the EOIC method, I have found that it is best to set the intake valve when the exhaust valve is fully open (or damn close, but not past). Strangely, the intake valve lash seems to be looser when the exhaust valve is damn close to fully open, versus just opening. I thought that was strange because the intake valve has no reason to be on anything other than its base-circle when the exhaust valve begins to open (ie, well past intake stroke). I wouldn't think overlap would play a role until the exhaust valve is beginning to close.

Next, when using the EOIC method, I have found it is best to set the exhaust valve when the intake valve just starts to close and no later. At that point, I can fit the 'largest' feeler gauge between the valve tip and rocker roller and if I wait until the intake valve is close to closing, I can't fit that same feeler gauge between the two points. Seems strange once again because the exhaust valve isn't set to open until after the power stroke; at this point we are just finishing the intake stroke.

Does any of that make sense to you guys? It doesn't to me, but once I noticed that trend, I focused on it and it was consistent for each cylinder.


The cam specs that my friend and I measured while the cam was still in the engine were:

.552 lift using a 1.5 ratio rocker
248 degrees duration at .050
112 LSA

Not exactly a radical cam.


After reading what I posted, in both cases, one of the valves is close to max lift. This means the spring is putting max pressure on the shaft. I wonder if the shaft is lifting slightly? This is the shaft mount system that I have, torqued to 20 ft lbs using ARP torque lube and grade-8 bolts:

[img:left]https://drive.google.com/file/d/0B47FH99TbpHuTEdkb3d4eENwUmc/view?usp=sharing[/img]

As long as you are consistent you are good to go. Use the spot that you can use the largest feeler gauge in, which will help you keep a close eye on the condition of your parts. All this stuff moves and bends slightly under load, and that is why the difference. Different spring loads in different places bend/compress the parts just enough to show up. It gets significant on a rollercam with 340lbs open pressure and 900lbs over the nose.

FWIW I just degree'd the cam in my 340...I watched the dial indicator thru 360 degrees of the cam rotation. For maybe 60% of the time there was absolutely no change then it would move as the valve would be opening and closing...then back to no change.
I think Greg is correct that other forces come into play.
My cam was a ST-21 Racer Brown. I have no idea what others do on a dial indicator when on base circle.
The ticket is to be consistent with the feeler gauge and with the position of the opposing valve...

When I set my lash a few weeks ago it was my first time. It really helped me to use a set of GO-NO-GO Feeler Gauges. Each feeler gauge steps up .002 at the tip, so you know for sure that if you can pull the tip through you didnt set the lash tight enough.

We used to set the lash on Duntov small blocks with motor running and rags all over....012 and .018

I use the Mopar method.

I use the EOIC method and I have a starter button on my firewall, once I have the valve covers off it literally only takes me a couple minutes to check all 16 rockers.

As soon as the exhaust rocker starts to move down, check the intake rocker lash.
Then bump the starter button so the intake rocker goes all the way down and as soon as it starts to move back up(close), check the exhaust rocker.

Also, as your bumping the starter button, you can try to push the feeler gauge in there, which gives you a feel for the rocker as far as how much it travels while having lash and it helps you to know when to check and set it.
It's a very easy method.