I have the truck in sig. I'm installing a set of tsp 2.5 5.3 862 heads milled .030 with stock mls gaskets, new ls7 lifters, and a tsp 220/220 .581 112 cam.

I've been reading for the past hour several posts on pushrods lengths etc...

I have no time for down time to order pushrods after using a checker. I have a few sets of comp hardened pushrods. 7.425's, 7.4's, and 7.375's. Should I order 7.350's and 7.325's just to be safe? That should be the last thing I need to get besides dexcool.

Also if my lifter trays look good will they be ok with the ls7 lifters?

Thanks a bunch,
Steve

 

I would pick up a length checker (we sell the comp ones for $19.99), this would be the best way to figure out what you need with no guess work involved.

 

Also, replacing the lifter trays are cheap insurance.

 

7.375s. Trays will be fine unless you have over 150k miles then id replace them. I always seem to have least amount of valve train noise with 1 1/4 to 1 3/4 turn on the rocker bolt from 0 pre load (just snugged up with your fingers)

 

Every pushrod is the same out of the factory, and the pushrod gos nearly straight down from the base of the head/block, mill.030 get.030 shorter pushrods this will get you within .005 every time (plenty safe) the cam base circle 'should' be known by the company that sells it to you but they never do, the comp xer cams are all prettyclose when I've checked them, I've always needed a 7.4. Really big cams might need a longer one.

 

It's got 154,xxx. So 7.375 with my .030 mill sounds good! Won't be any more money outta my pocket!

 

I've read and somewhat understand the ls7 lifter being "taller." but it's not actually taller?! That's what has me confused.

 

This is definitely not true. Since the pushrod does not run perfectly perpendicular to cylinder head deck, this is a geometry, and unfortunately (due to all variances in the motor: camshaft base circle, cylinder head deck, block deck being off from GM, different lifters that have different plunger depths or preload specs, etc., and etc.) cannot be calculated without knowing all of these variances exactly. Since we do not have all of this information, you will need to measure.

 

base circles, even with the same lobes used, can vary quite a bit! We've checked a standard 228 XER cam here with a completely stock LS1 long-block, and it needed 7.350"...everybody and their dog on the internet would have sworn that completely stock engine would have needed 7.400". Why is that? It has nothing to do with the size of the cam in terms of duration or lift either.

 

The lifter body isnt taller. The plunger depth is shorter.