mfoti

2007 LS2 stock engine. I installed a new cam but DID NOT touch the heads or lifters. I measured stock cam base circle at 1.518. I measured new cam base circle at 1.468. Therefore, since nothing else changed I should need a 0.025" longer pushrod correct? Well, when i use the comp cams pushrod checker I get 10.75 turns to zero lash corresponding to 7.337. If a add .040 pre-load i get a 7.377 pushrod? This isn't making any sense. What am i doing wrong?

mfoti

Ok, i think i see part of my problem. Stock pushrod is not 7.400. It is 7.375. With that said what preload should i be targeting?

mfoti

Anyone? I have been searching for hours and I cannot find a recommended preload for an ls2 lifter. I see ranges from 0.02 to 0.08. A stock setup must have close to 0.05?

ErnieN85

Try asking in the engine mods forum (general)

mfoti

Thanks. I think i have it figured out after reading comp cams valvetrain guide and talking with texas speed. For those who are not aware you cannot measure pushrods with a caliper and purchase based on that measurement because the size of hole in the rod offsets that total measured length. Essentially, pushrods are sold as "gauge length" as opposed to actual length. A 7.400 pushrod does not measure 7.400 with a calipers. It is an adjusted length associated with the adjustable gauge measuring device. If you purchase pushrods advertised as 7.400 they will actually be LONGER than stock despite contrary belief.