Pushrod questions
Pushrod questions I am trying to understand 2 things about pushrods. I understand thier function but do have 2 questions. 
What are the advantages of going with chromoly pushrods over stock? Are they that much stronger that will make a difference in driveability?
How will the length make a difference in compression? Stock Vs 7.350" Vs 7.300. The heads are PRC LS6 CNC Ported Heads with competition CNC valve job and PRC double springs kit from Texas Speed .100" 72, .200" 149, .300" 205, .400" 255, .500" 287, .600" 307, .625" 310, the cam is Texas Speeds Magic Stick 4 Cam (239/242, .649"/.609" 111 LSA) and stock rockers.
Thanks
What are the advantages of going with chromoly pushrods over stock? Are they that much stronger that will make a difference in driveability?
How will the length make a difference in compression? Stock Vs 7.350" Vs 7.300. The heads are PRC LS6 CNC Ported Heads with competition CNC valve job and PRC double springs kit from Texas Speed .100" 72, .200" 149, .300" 205, .400" 255, .500" 287, .600" 307, .625" 310, the cam is Texas Speeds Magic Stick 4 Cam (239/242, .649"/.609" 111 LSA) and stock rockers.
Thanks
Last edited by -=Modified=-; Nov 19, 2006 at 01:11 AM.
Only time they will affect drivability is if the length is wrong. Pushrods on the stock rockers will determine the lifter preload. Too much will hold a valve open, too little will be noisy or in an extreme case won't open the valve enough. The lengths you mention will be too short and likely loose even with the valve close.
As for the material, the pushrods bend when the valve opens (a very small amount) and also act like springs. Stronger pushrods with thicker walls will reduce this affect with the higher strength springs and higher RPM of an aftermarket cam as compared to stock.
As for the material, the pushrods bend when the valve opens (a very small amount) and also act like springs. Stronger pushrods with thicker walls will reduce this affect with the higher strength springs and higher RPM of an aftermarket cam as compared to stock.
Vettenuts is on the money... The chrommoly PRs are stronger and wont flex as much as mild steel.
He's also right about keeping a valve from fully closing or opening in extreme conditions, but you would have to bottom out or top out the lifter plunger. Usually its sinply a matter of valvetrain clatter. Try and get your preload close to where it was stock. this is usually around .070 - .080 lifter preload.
He's also right about keeping a valve from fully closing or opening in extreme conditions, but you would have to bottom out or top out the lifter plunger. Usually its sinply a matter of valvetrain clatter. Try and get your preload close to where it was stock. this is usually around .070 - .080 lifter preload.
