I will be running Comp XR275HR with 317 heads milled .40.

Has anyone ran this combo to recommend length of pushrod? 7.40, 7.45?

 

if you mill .40 the pushrods needs to be .40" shorter. But then the cam also has a .50" smaller base circle than the stock cam. 7.40" would work just fine for you IMO.

 

i asked a similar question and the only answer i got was "you have to measure them"

 

Thanks GMCtrk.

454 I have measuring tool but once I get truck apart I can't measure and wait for pushrods to arrive as this is my dd. The XR275HR is a pretty common cam so I was just hoping someone has ran something similiar. I was waiting also for the measure with tool response after I posted.

Rob

 

How did you know what the base circle of the cam would be?

 

Factory pushrods are 7.38. Most aftermarket cam manufacturers recommend 7.4 pushrods for their cams with stock heads. HirdleJ has posted pics of LS7 lifters showing that the cups where the pushrod sits are actually a little taller than his original (04) stock lifters, and he had to go to a shorter pushrod as he had too much lifter preload which was causing noise and could have potentially damaged the lifters, maybe even the camshaft. Not sure if you're changing lifters or not, but it's something to think about. WCCH likes to see .040 to .080 of lifter preload, with .060 being optimum. Personally, I'd measure them, just to be safe. I'm going to be putting an LQ9 together with a Vinci Trucker cam, and WCCH StageII 317's which I plan to have milled about .030-.035....I would love it if I could re-use my current Comp 7.4 pushrods, but my gut tells me that after I measure I'll be investing in a set of 7.35's. I'd bum a ride to work for a few days or order two sets of pushrods and return the ones you don't use...if you take out a set of lifters or wipe out some cam lobes you'll be without your daily driver for even longer

 

i understand that, my truck is my dd too