Hi Everyone,

I am doing a cam swap and am wondering if I need to replace my pushrods? I am pretty certain everyone will tell me yes, so my next question is, who has the best deal on a set of chromemoly pushrods in the stock length (7.400)? Should I buy a new set from GM? Let me know whats the hot ticket....

Thanks In advance,

Russ

 

First, are you sure you want the stock length? Aftermarket cams change the cam base circle and could require a different length. Skoggins-Dickey sells the Manley's, they are excellent pushrods.

 

And the best way to determine the correct PR length is with a solid lifter installed and an adjustable PR length checker. Doing just a cam swap makes this impossible because you have to take the heads off to get at the lifters so, risking verbal diarreah, this is what I've learned so far.
The way a lot of guys check pr length with stock rockers and hydraulics in the car is to use a pr length checker and with the cam on the heel for the #1 cylinder intake valve tighten the rocker until you have 0 lash. Then you should torque to 22ft/lbs. and note the amount of turn you have between 0 lash and 22ft/lbs. You should have between 1/2 to 3/4 turn.
Having said all that, when most cams are ground they make the cam base smaller to accomodate the larger lobe lift, because the lobe can only grow to ~.100" at peak lift less that the cam journal radius or you won't be able to get the cam past the bearings. This means that distance between the nose and the center of most cams is the same, the cam base circle changes to create more relative lift. I thought this wasn't significant until I installed my cam and measured my pushrod length the correct way, taking into account tip wipe, and pr length. With my stock rockers in place the car wanted 7.4" pushrods even though I was using almost .100" more lift. And this was on AFR heads but stock LS1 length valve. Then I installed Harland Sharps and found I needed 7.375" PR's. I probably need to shim them and go back to 7.4" PR's...

 

Actually, I plan to do a swipe test with the hyraulic lifter by using checking springs and white out on the valve stem.

 

I never thought of that. I have the checking springs. I didn't think of using whiteout. I tried sharpie but didn't get enough pressure to wear them. I might have if I rotated the engine 50 times, but whiteout would probably give you a pattern right away. Thanks!

 

Haven't tried it yet, hoping it works. If you try it, would be interested in your results.

 

Use white shoe polish. White out is tough and will be hard to show wear pattern. My .02

 

does anybody know who might have the best price?

 

The Manleys are pretty reasonable at Skoggins.

 

KIWI

 

Sounds like another good idea. Have to check that as well.