Im going to order this cam kit but the problem i have is that i dont know what size of pushrods to get since im going to get the ls7 lifters. My engine is a 5.3 with 862 heads. Anyone done this before?

 

Can't be 100% sure without measuring. It would be a good idea to order a couple lengths measure and return the wrong sizes. 7.375, 7.4, 7.425 should cover the bases.

 

Yea well i've been reading and I think it should be around 7.35 since the lifters are around 0.50 longer well the cup is. So I think im going to go with those for now. I am ordering a pushrod checker just in case.

 

I've heard the rods need to be shorter than 7.400 - I'd measure than let me know I need to do the same soon

 

I'm running a 7.400 on .20 milled 862

 

I ran 7.350 with ls7 lifters and heads milled 0.03 and they were to short. It was very noise and the rockers were not in the middle of the valve stem. I put 3.375s in and they are much quieter and the rockers are back to being in the middle of the valve stems. Even though the Ls7 lifters are a 0.05 taller that doesn't mean you need a 0.05 shorter push rod, at least from my experience.

 

The height of the lifter cup when not preloaded does not matter. It is the preloaded height that you care about. LS7 lifters are now the standard replacement lifter for every LS engine and they are direct replacement. That means you can't assume you need shorter lifters simply because the unloaded lifter cup sits higher. Here's a link to a thread created by a guy who works on these engines at GM. He is more than just a mechanic, likely an engineer but I'm not 100% sure what his position is.
The Anatomy of a Hydraulic Lifter - Corvette Forum

 

Great article, however the pix will not load...Get the "spinning beach ball" treatment....Old post I guess, and yes, i am a member there as well..Tried to look at the pix by logging in but that didn't help either..

Yes, must be a GM engineer by his replies on the links in the post...

Great info for all....Thanks!

 

No problem. That pictures load fine for me on my PC and phone

 

Just get the tool and measure, it's not rocket science...