Milled Heads & Pushrod length
Milled Heads & Pushrod length I have asked this question and I have gotten different answers. I'm getting ready to put my heads back on. I had them milled .030. I have a Comp 222/222 .563 cam. Do I use standard 7.4" pushrods or shorter 7.35". And explain why...... 
TECH Apprentice
Joined: Oct 2002
Posts: 310
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From: san Antonio
Re: Milled Heads & Pushrod length You need to use shorter because if you don't you will wear out valve train components quicker. Having too short or too long of a pushrod causes the rocker arm to not contact the valve in the "ideal" spot. Click on the following link it explains it a little better... http://www.grapeaperacing.com/GrapeA...vegeometry.cfm
TECH Fanatic
Joined: Nov 2001
Posts: 1,975
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From: SW Florida
Re: Milled Heads & Pushrod length Your lifter preload question is really very simple:
The Comp cam you have has a base circle approx .060" smaller than the stock cam (we measured them). That gives you a cam 'centerline to lobe heal distance' .030" smaller than the stock cam.
That in itself would require a pushrod .030" [longer] than stock in order to retain the stock spec lifter preload.
You have milled the heads .030"
That in itself would require a pushrod .030" [shorter] than stock in order to retain the stock spec lifter preload.
Looks to me that you need to keep the stock length pushrods in there. It's pretty simple math if you ask me.
The Comp cam you have has a base circle approx .060" smaller than the stock cam (we measured them). That gives you a cam 'centerline to lobe heal distance' .030" smaller than the stock cam.
That in itself would require a pushrod .030" [longer] than stock in order to retain the stock spec lifter preload.
You have milled the heads .030"
That in itself would require a pushrod .030" [shorter] than stock in order to retain the stock spec lifter preload.
Looks to me that you need to keep the stock length pushrods in there. It's pretty simple math if you ask me.
Re: Milled Heads & Pushrod length The safest way is to measure preload on your lifter.I did the math on my setup and figured I needed the stock length pushrod.Then I measured the preload and found out I needed the 7.350's.
There are still people driving around with .010+preload with no problems,but I'm not one of them
There are still people driving around with .010+preload with no problems,but I'm not one of them
