hey im doing a ms3 cam swap on my 98 trans am. i bought new comp rpm ls1 lifters comp 7.400 pushrods,dual valve springs, ls6 intake, and pasesetter longtube headers.
my questions are did i buy the right length pushrods and also whats the method on how to set the lifter preload on the ls1. i was looking on all different posts and couldn't get a definitive answer on pushroad length. most said that the stock 7.400's are perfect and some said there to short. did i buy the right ones? and im so used to working on good ol 350 chevy (my first ls1) so i dont know the lifter preload method.
HELP!! thanks.

 

bump any help??

 

Here's what I've found that works really well. Set #1 piston to just before top deal center, so you know that both of the lifters are on the cam base circle. With the head installed, put in a pushrod length checker at ~7.300" as measured with a caliper. Now install the pushrod length checker, and rocker arm and torque the rocker arm down to 22ft/lbs. The pushrod should still be loose meaning that you have less than zero preload. Now adjust it longer till it barely touches the rocker arm, now you have zero preload. Remove the pushrod checker, and measure it. Now add the amount of preload you want and you'll come up with your length.

I recently did this, and with my setup, I found that zero preload measure out to be 8.038". 0.060" preload put me right at 8.1", which just happens to be a common size.