Austinma62

OK. So we checked the pre load on the 7.350 push rods from TSP with stage 2.5 LS6 heads milled .030. running the stock GM headgasket running .051 compressed thickness. And we came up with .090 preload. What preload is recommended? And what pre load is ran in stock form? The Comp cams manual recommends between .020-.040 preload. What do you guys think?

ZeeOSix

You running Comp Cams lifters? I'm assuming the Comps Cam recommendation is just for their lifters (?).

Austinma62

Im using LS7 lifters and the stock rockers were torquer down to 22 ft lbs.

ZeeOSix

When Comp Cams recommends 0.020 to 0.040" pre-load, are they saying for any lifter?

Lifter plunger travel differs between lifters. The LS7 lifters have around 0.170" of travel per the attached chart below, so IMO your 0.090" pre-load isn't far off. Someone here actually measured the LS7 plunger travel and got somewhere around 0.200" if I recall correctly.

outkast6991

iTrader: (34)

I'm running .025 on my ls7's

Austinma62

I'm confused with that chart. I looked at my ls7 part number and it doesn't match any of those.

ZeeOSix

What part number do you have?

dodson55

iTrader: (18)

i think ideal is around .045 to .060 i am running .090 on mine and it does fine

Austinma62

28-12499225 GM ls7 lifter kit

Austinma62

your running ls7 lifters also?

joecar

12499225 is the part number for the kit of 16 x 17122490 lifters (i.e. the last row of the chart posted above by ZeeOSix).

Austinma62

Ok, so your saying the .082 preload would be ideal for the LS7 lifters?