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Profiler27' 07-26-2009 04:06 PM

push rod length questions
 
I have a 502 Mag MP that we freshened up a few moths ago and I went with a bigger cam , Crower lifters, and had the ecu re-flashed as well. My question is, how will it effect the valve lift and the valve timing if the push rods are a little on the long side? We marked the top of the valve and rolled the motor over and roller seemed to be traveling on the bottom side of the valve stem and when we checked the fulcrum (spelling) the push rods were top long according to the tool we used! Another question I have is how will this effect the over all performance of the motor, will I get the max lift of .542 on the intake valves and the .535 on the exhaust valves?

Thanks for the help,

blue thunder 07-26-2009 06:01 PM

It will side load the valve which will cause the guides to wear quickly. Your lift will be fine as long as its staying on the top of the stem.

Profiler27' 07-26-2009 09:30 PM

I was told by running a long push rod I would lose some valve lift, didn't know if anyone has run into this problem or not, thanks

jeffswav 07-27-2009 08:32 AM

Here is a article RMbuilder sent me when I adjusted mine. http://www.popularhotrodding.com/eng...variables.html

fbc25el 07-27-2009 09:14 AM

Go to www.mid-lift .com and that will explain everything.

Young Performance 07-27-2009 11:07 AM

The only way that you will change the amount of lift of the cam is to physically change the cam. If the pushrod is to long or to short, you will prematurely wear the guides as Blue Thunder said. You will still have the same amount of lift with the right pushrod or the wrong one. You really need to get it fixed.
Eddie

Panther 07-27-2009 12:34 PM


Originally Posted by Young Performance (Post 2918897)
The only way that you will change the amount of lift of the cam is to physically change the cam.

Or a 1.8 rocker arm instead of the regular 1.7, it will give slighly more valve lift. Gotta check clearances though.

I know some guys who are running 1.8's on the exhuast side to give a little more flow and act like a split duration cam on crappy heads.

Rookie 07-27-2009 12:41 PM


Originally Posted by Panther (Post 2918989)
Or a 1.8 rocker arm instead of the regular 1.7, it will give slighly more valve lift. Gotta check clearances though.

I know some guys who are running 1.8's on the exhuast side to give a little more flow and act like a split duration cam on crappy heads.

I run 1.8's on my intake side for more lift, and 1.7's on the exhaust. This was done on a dyno and there were only gains for my setup on the intake side.

DORaymond 07-27-2009 01:58 PM


The only way that you will change the amount of lift of the cam is to physically change the cam. If the pushrod is to long or to short, you will prematurely wear the guides as Blue Thunder said. You will still have the same amount of lift with the right pushrod or the wrong one. You really need to get it fixed.
I believe if the geometry is too far off, you can change the effective lift of the valve due to the angle the rocker makes with the valve stem. Remember the rocker tip moves in an arc.

Panther 07-27-2009 02:27 PM


Originally Posted by Rookie (Post 2918994)
I run 1.8's on my intake side for more lift, and 1.7's on the exhaust. This was done on a dyno and there were only gains for my setup on the intake side.

Nice!!:ernaehrung004:


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