So ive just about seen every vidoe on YouTube and read a bunch of post on how to measure the length. I am very confused though as to the measurements i am coming up with. Using the e.o.i.c method on at a base pushrod length for zero lash i am about 7.440 using the comp cams checker. I have 7.450 pushrods from tsp and at zero lash i can only get them to tighten down to a half turn of the rocker bolt to the 22ftlbs. Idk if using the comp cams trunion upgrade is making the amount of turns be less? Due to the allen bolt provided being shorter than the stock rocker bolts?. My question is why is my reading so high just to get zero lash? I have a upper ls2 cam gear with a stock ls1 crank gear and ls2 chain idk if this can affect the timing?

 

Mods are prc 225 heads 62 cc, stock ls1 block, gm mls head gaskets, ls7 lifters, torquer 2 cam. Any help is greatly appreciated

 

Are you saying you got zero lash with the pushrod checker at 7.440"?

 

yes 7.440 just to get to zero lash which i know its way too much thats why i am confused as to why im getting this measurement. The way im checking is when the exhaust valve is about to open i check the intake when its fully closed. As a starting point i checked with a stock push rod and even with the rocker bolt torqued down 22 ftlbs the rocker had tons of lash. And checking with my tsp pushrods that are 7.450 from zero lash to 22 ftlbs of torque it only takes a half a turn i know this is not enough preload. I need suggestions maybe im checking wrong??

 

A couple things.

-https://ls1tech.com/forums/generation-iii-internal-engine/1814456-how-wipe-pattern-roller-rocker-pushrod-length.html#post19085422 Start with post #13 and read, re-read this several times. You do not need to torque anything to 22ft/lb yet.
-Use calipers instead of pushrod checker turns to measure the length.
-Mine were all 7.48x at zero lash. I'm using different lifters and PRC 225 heads.
-TSP also told me to use 7.450 length, but after measuring I decided to be more precise and ordered 7.525".

So your longer zero lash measurement isn't out of the ordinary, depending on your setup. I know exactly how you're feeling, because I was doing the same thing. Best bet is to forget what you're doing and follow the guide step by step. It'll click and you'll be in good shape.

 

Hell I had 7.7! Different lifters, different heads, etc. to me it seems that your bolt turn sort of confirms you need longer pushrods.

The rotation should only be used to confirm the measurements with the calipers

 

That's what I was thinking re: needing longer ones. I have a guess at what he'll end up with but don't want to skew his thinking

 

I ended up going out and getting myself a 8"digital caliper like it you had mentioned, best decision lol i was able to really dial in my measurements. At base zero lash im at 7.435 and to add my 0.080 preload it put me at roughly a 7.51 pr's and i checked the number of turns it took to tighten down the bolt, it took 1 1/4 turn. The measurements were pretty consistent on both banks so im going with some 7.500 , thanks for the help

 

That's awesome! Congrats on getting it done.

Oh, and when you order make sure to tell the vendor you measured overall length with calipers. They'll make any necessary adjustment.

 

That's great! The calipers take the guesswork out, so you can order with confidence.

 

The prc heads have a thicker deck than stock heads. That is why you have longer than stock pushrods.