godspeed1976

I used some LS7 lifters in a recent round of mods on my 94 Formula. Yhey said direct replacement, and they were cheaper so it seemed like a good choice. They were not direct replacement. Yeah they fit in the bores, but they are a lot shallower then OEM LT1 lifters.

I used them in conjunction with the .026" Victor Rienz head gaskets and some GMPP 1.6 rrs, Comp 983 dual valve springs, Ti Retianers and locks, as well as some new stock valves (nothing fancy just stock replacements). My block is not decked, nor were my heads milled. However when I put it all together with 7.2 pushrods it ran like it had a massive cam in it. Not in the good way either. Granted having 6 month old gas in it could have played a part, but not entirely

Knowing something was wrong, I opened it back up and checked the valvetrain geometry. It was all messed up. The rocker tips were way to far over on the valve. I measured for the correct pushrod size, and turns out I needed a 6.881 pushrod for the rocker tip to stay centered on the valve.

I dunno bout you all, but that is a pretty big jump from 7.2 pushrods to me! I'm actually kinda baffled. I haven't tested the new pushrods yet (putting them in this weekend), but I did check one after I measured, and the geometry looks right now. Because its such a huge jump in size it has me questioning...we will see this weekend.

Any similar situations?

Low N Slow

iTrader: (4)

I used the same lifters, Comp Pro mags 1.6 rockers, .029 gaskets, heads shaved, block decked and ended up with 7.00" pushrods.

Purple95Z28

iTrader: (6)

Looks like your difference there is mostly in the headgaskets?

Mine is using 7.200 pushrods with LS7 lifters, geometry checked out fine with the rollers centered on the stems

nutiger

iTrader: (2)

If the LS7 lifter is shallower then OEM LT1 lifters, wouldn't you need a longer pushrod? You said 6.881, did you mean 7.881? If you need a shorter pushrod, I would think this is better.

Elliott's94Z

iTrader: (12)

From what I understand you have to use a longer pushrod with the LS7 lifters. I have thought about running these when I rebuild but it seems 50/50 from what I'm hearing about them working properly on our LT1.

Jditlfm

iTrader: (26)

I agree. I think a lot of the change came from the head gasket

ElkySS

iTrader: (6)

well i put in ls7 lifters when i put in my Ai cam, 1.6 rr, non-sa rockers. stock, un opened motor otherwise. used a 7.150 pushrod. works fine

StealthFormula

iTrader: (35)

The difference between lengths can't be right, definetly isn't that much of a difference if a difference. When I measured my geometry with the stock lifters, .026 Reinz, milling of the heads, etc. etc. I ended up with a 7.100" pushrod. I swapped the lifters for LS7's and came up with the same length.

godspeed1976

Thats very strange since the cup is noticeably more shallow then the OEM lifter. Several people have measured it to be a .1 difference. So for you to have swapped OEM LT1 Lifters with a LS7 lifter that is .1 taller it should have thrown your geometry off since you are running a longer pushrod.

StealthFormula

iTrader: (35)

Thats what I was expecting but I measured and came up with the same length so I left it at that and it works great.