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Re: Push Rod Length
[Re: Wolfe440]
#947133
03/10/11 02:36 PM
03/10/11 02:36 PM
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Joined: Oct 2005
Posts: 8,853
Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 8,853
Ontario, Canada
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Quote:
I should have worded it a little different, I was basically saying you need to get it to that point before you change the length of the push rod after adding rocker bars shims to correct tip contact point.
You should have read the rest of my post and also hi-lighted where I said to use rocker bar shims to change the contact point on the valve stem tip.
Always use the correct length push rod never a shorter one, your goal here is to correct the geometry on the rocker motion all the way through the cam cycle. Short push rods on adjustable valve trains cause many issues and one is it puts a trememdous side load on ball adjusters especially on small blocks.
I read your whole post and I know what you're saying. However, trying to get perfect geometry on anything but an all out race motor is for the most part an effort in futility, particularly for anyone but a specialized Mopar engine builder with access to a wide variety of parts. To do it "right" you need the rocker to be perfect - anything else is just a band-aid. For example, let's say the contact point on the valve tip is to the outside and needs to be moved in. The only options here are a) swap rockers b) add lashcaps c) mill the pedestals. If the contact point is towards the inside, the options are a) swap rockers or b) add shims. The problem with shims is that they're consistent in thickness so the shafts don't seat properly in the pedestals once they're installed. You've solved one problem but now you have another. And since the perfect geometry is tagetted at the midpoint of lift, it all goes out the window if you switch to a bigger or smaller cam.
As for the pushrod length affecting side loads on the adjuster, again, in an all out race motor with a huge cam I'm in total agreement with you. But with a cam such as the OP is using and the subsequent rocker angle, the difference in the sideloads on the adjusters would be minimal and well within their operating parameters with a slightly shorter-than-perfect pushrod.
The bottom line is that if the OP has to order pushrods he may as well do it right and order the perfect length. All I'm saying is if he has a set or access to a set that's slightly shorter, they'll do just fine in his application.
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Re: Push Rod Length
[Re: Wolfe440]
#947138
03/10/11 05:37 PM
03/10/11 05:37 PM
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Joined: Aug 2005
Posts: 4,799
ILL
MLR426
master
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master
Joined: Aug 2005
Posts: 4,799
ILL
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Quote:
Did exactly that very procedure, a procedure I have done many times before with consistent success. I also have a second muscle head person assisting and we have done the procedure several times with the same results from 1/2 turn to 3/4 turn preload. No change, we're stumped.
I agree posted above my push rod length probably can have some fair tolerance for length as long as the geometry with the rocker is right and adjuster falls in its correct range.
Looking again at this sharp grade very short duration 564 high lift cam, could my lifters be skipping... catching air (per-say), I ponder would stronger springs keep them planted and reduce the rocker noise?
What is the open load of the springs that are in use ? Have they been rechecked with a gage against the spec they say they are ? On a xe274 I used 120 on the seat and close too 300 open load I believe and that is good for rpm up too 5,500.
logan426
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Re: Push Rod Length
[Re: MLR426]
#947139
03/10/11 06:08 PM
03/10/11 06:08 PM
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Joined: Feb 2007
Posts: 216
New Port Richey, Florida
Wolfe440
OP
enthusiast
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OP
enthusiast
Joined: Feb 2007
Posts: 216
New Port Richey, Florida
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Quote:
Quote:
Did exactly that very procedure, a procedure I have done many times before with consistent success. I also have a second muscle head person assisting and we have done the procedure several times with the same results from 1/2 turn to 3/4 turn preload. No change, we're stumped.
I agree posted above my push rod length probably can have some fair tolerance for length as long as the geometry with the rocker is right and adjuster falls in its correct range.
Looking again at this sharp grade very short duration 564 high lift cam, could my lifters be skipping... catching air (per-say), I ponder would stronger springs keep them planted and reduce the rocker noise?
What is the open load of the springs that are in use ? Have they been rechecked with a gage against the spec they say they are ? On a xe274 I used 120 on the seat and close too 300 open load I believe and that is good for rpm up too 5,500.
logan426
The springs are what comes on the Edelbrock Performance heads, all I could find is the springs are 120-pounds seat load at the as-delivered installed height of 1.880 inches, and can handle up to .600-inch lift. I can't find an open load spec.
I also checked Comp Cams web site, I could not find a recommended spring for the cam. May have to call to get it. The heads are assembled new out of the box.
Last edited by wolfe440; 03/10/11 06:13 PM.
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Re: Push Rod Length
[Re: Stanton]
#947141
03/11/11 03:58 PM
03/11/11 03:58 PM
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Joined: Feb 2007
Posts: 216
New Port Richey, Florida
Wolfe440
OP
enthusiast
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OP
enthusiast
Joined: Feb 2007
Posts: 216
New Port Richey, Florida
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Quote:
Ok, I'm going to assume these are single springs. A Comp 911 has an installed height and seat pressure similar to yours ( 1.9 / 122 ). At lift close to what you're running they have 328 lbs of open pressure. They're only recommended for up to .500 lift.
The recommended spring for your cam is a 924 - dual spring. 1.9 inst height, 112 lbs on the seat, about 299 at your lift and recommended for only .525 lift (go figure!).
Since the recommended spring has even less open pressure than the other, I doubt that's the issue.
Although you should probably check what your springs are.
Yes they are single spring, and with a lot of searching the lift is advertised for these springs at 300lbs. Since the cam is 564 lift I am not in a range of spring that would give me confidence they can handle this cam.
I agree I first need to have my springs checked and not just assume because they came on Edelbrock Performance heads that their even the 120/300 springs they advertise.
I will run with this and see where it takes me. Will report back later.
Thanks for all the help! 
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Re: Push Rod Length
[Re: MLR426]
#947143
03/12/11 04:48 PM
03/12/11 04:48 PM
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Joined: Feb 2007
Posts: 216
New Port Richey, Florida
Wolfe440
OP
enthusiast
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OP
enthusiast
Joined: Feb 2007
Posts: 216
New Port Richey, Florida
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I'm using a 1.5 rocker. I was able to find the spec sheet on the cam, which is a miracle considering my filing is so disorganized  I could kick myself for not looking at it closer, yet I thought I had a conversation over this with someone?? Not even sure if we were discussing this motor, its been a year or so. Spec sheet says this cam calls for a dual spring set up with 112lb at seat and 355lb at open load. My existing springs are at least 50lbs less than the open load requirement @1.200 I can't seem to double verify if these cams are noisy even with the proper springs, yet I can very well see why it would be prone. Still not sure if I want to keep the cam itself, this is a street car and it needs to sound right. I wanted the high lift and short duration for idle quality, this car has A/C. I guess I will first go with the right springs, if the soft clacking gets at least 50% quieter I can probably live with it...I hope.
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Re: Push Rod Length
[Re: Stanton]
#947144
03/12/11 07:29 PM
03/12/11 07:29 PM
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Joined: Oct 2003
Posts: 3,698
NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Quote:
The recommended spring for your cam is a 924 - dual spring. 1.9 inst height, 112 lbs on the seat, about 299 at your lift and recommended for only .525 lift (go figure!).
How do you figure the 924 is only recommended for .525 lift?
By the Comp chart, set up at 1.900, the spring will handle .600 lift with ease. Probably a true .665 net lift???
Its not the right spring for his app...IMO...but would probably work....I guess if you kept the RPMs 6k or less it they would work.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Push Rod Length
[Re: Von]
#947145
03/12/11 10:59 PM
03/12/11 10:59 PM
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Joined: Oct 2005
Posts: 8,853
Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 8,853
Ontario, Canada
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Quote:
How do you figure the 924 is only recommended for .525 lift?
'cause in the Comp catalog on the line that says " Max. Rec. Lift" and in the column for the 924 spring it says .525 !!
Quote:
By the Comp chart, set up at 1.900, the spring will handle .600 lift with ease. Probably a true .665 net lift???
Sure, and when you buy a tablesaw there is a warning that says not to use it without the guard in place, but people do!
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Re: Push Rod Length
[Re: Stanton]
#947146
03/13/11 11:14 AM
03/13/11 11:14 AM
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Joined: Oct 2003
Posts: 3,698
NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Quote:
Quote:
How do you figure the 924 is only recommended for .525 lift?
'cause in the Comp catalog on the line that says " Max. Rec. Lift" and in the column for the 924 spring it says .525 !!
Quote:
By the Comp chart, set up at 1.900, the spring will handle .600 lift with ease. Probably a true .665 net lift???
Sure, and when you buy a tablesaw there is a warning that says not to use it without the guard in place, but people do!
We set up a set of 924s last night......No reason they wont take .600 plus lift with ease. Seat and open psi were both a little heavier than what the spec chart shows also....not much but a few lbs.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: Push Rod Length
[Re: Von]
#947147
03/13/11 02:18 PM
03/13/11 02:18 PM
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Joined: Feb 2007
Posts: 216
New Port Richey, Florida
Wolfe440
OP
enthusiast
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OP
enthusiast
Joined: Feb 2007
Posts: 216
New Port Richey, Florida
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I'm doing more searching and finding agreement that these XE cams are noisy, correct springs or not. Quote: "FWIW, I called Comp Cam again and got a different tech. He told me pretty much the same thing that I would have some lifter noise with the XE cams." http://www.forabodiesonly.com/mopar/archive/index.php/t-5955.htmlIf Comp Cams is saying "some lifter noise" we know their being conservative. Found a few Chebby guys complaining as well. One person posted Comp Cams told him on his XE hydraulic go preload from half to one full turn, should help reduce noise. Yea right, just keep cranking the preload down boys until its quiet... who cares if your valves don't even close...pfft*! 
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Re: Push Rod Length
[Re: RapidRobert]
#947149
03/13/11 03:39 PM
03/13/11 03:39 PM
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Joined: Feb 2007
Posts: 216
New Port Richey, Florida
Wolfe440
OP
enthusiast
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OP
enthusiast
Joined: Feb 2007
Posts: 216
New Port Richey, Florida
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Quote:
Quote:
In this case should I get a push rod gauge and use it to determine my push rod length? Go to zero lash and .030 more for a final length?
Not sure if .030" is right (I'm not a cam guy) but yeah that/1-1&1/2 threads/base circle. If you're handy w taps/dies I'd make or buy an adjustable pushrod & see what is the ideal length for your app & compare that figure to the ones you have & go from there that way you have as much info as possible to better make an informed decision. Also w the checker and a pair of light springs I would check the wipe pattern and Hughes' checks, again more info at your disposal
Well in fact for a test I have a set of Mancini hardened Docile factory style rockers and standard 3/8 9.315 pushrods, no adjustment offered of course. I took off the rollers and bolted them on and measured the preload of several plungers in the lifters with a dial indicator and they came in right at .035 which is right where they should be. So I ran it for a short time and nothing changes, still getting soft clacking.
Conclusion is that even when everything is right Comp Cams admits these cams are lifter noisy, I will second that. I'm clearly faced changing the cam if I want this to go away. Lot of other builds over the years so I got a few other cams on the shelf, probably don't have to buy a replacement, just sucks the motor is now in the car.
Then again I could get a louder exhaust system..
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