Okay, so I just took apart my 2001 TransAm to do a heads, cam swap.
I have a set of PRC stage 2.5 ls1 heads milled .020 62cc chambers, new lifters, trays, oil pump, timing chain, cometic .040 head gaskets, a howards 234/238 .637/.635 110 lsa. I have new lifters and need to get pushrod length. Can I use these new lifters with check springs to accurately measure pushrod length. I know how to use my adjustable pushrod gauge to get the measurement but have not ever done it with new lifters. I would just tack weld one of my old stock ones but they are different. Also I will be using a dial indicator to check ptv, can I do this with the check springs and new lifters? Please advise... and yes I searched it but didnt find exactly what I was looking for. Thanks in advance for your help, I have learned so much from this site.

 

For finding your proper pushrod length, you can use the "known length" method. Install the new (unmodified) lifter on the base circle, old pushrod, don't use checker springs here, and start tightening down the rocker until there is zero lash. From Zero lash, count the number of turns until the rocker arm bolt is fully seated. This will depress the lifter plunger. From there you can calculate the preload amount from the thread pitch of the rocker arm bolt. Subtract or add the difference from your old pushrod to your target preload amount. Now you know what length of new pushrods to order.

For PtV checking, you can do this with unmodified lifter, adjustable pushrod, checker springs, and dial indicator. Here is my writeup on that:
http://www.scribd.com/doc/137049285/...RAFT-20-Apr-13

good luck

 

Can't you just ask the lifter company what preload they recommend and I just add that to you zero lash length?