Now im concerned, i bought a set of LS7 lifters from SDPC and was going to put them in the LQ4 i just bought with my 7.40 pushrods from my 5.3 .

Damn it....

 

I bought 7.35s thinking they'll fit, but won't have any idea till I get them in and measure preload...All things being equal I think you'd want shorter pushrods if all you are doing is changing lifters, but it's all guess-work without knowing the base circle diameter of the cam. The higher the lift, the smaller the base circle...so I'm starting to worry 7.4s might be closer to what I need...It'll be interesting to see when I get everything apart, knowing murphy's law

 

Good luck, i'll let ya know what i find out when i get closer to install.

 

go with comp Rs lifters, I have broke many ls7 sets

 

I will be installing LS7 lifters next week in my otherwise stock 5.3L. I have a pushrod length checker here, and Comp 7.350" and 7.375" pushrods on the way. I will post up what I end up going with. I'm just waiting on gaskets and a few other things before I begin.

 

I remember reading a lot of bad stuff about the more expensive Comp lifters over on Tech a while ago, supposedly Comp's factory replacements aren't so bad, but their more expensive ones are/were problematic. If you're breaking many sets of LS7 lifters something else is going on, too long of a pushrod maybe?

 

l92's are heavier from having the GAY DOD.. i would deff reccoment changing them if your going to run a cam with higher lift tham .600 and spinning more than 6200!....

ls7s should be just fine . ~.050 preload and your good to go!

 

what about LS7 lifters with 7.400 will it be fine??

 

It's gonna depend on the base-circle of the cam; if you're running a cam with .610+ you might find that 7.425 pushrods might work better, the reverse is true if you're running a cam with .525 lift, the base circle would then be bigger, so the effective distance between the roller on the lifter and the pushrod side of the rocker arm will be shorter and closer to 7.3 might be best.

it's really hard to guess accurately since none of us short of engine builders know the exact base circle of a given cam lobe profile.

All things being equal, and if the only thing you were changing was going from stock lifters to LS7s, with the stock cam, then 7.4 pushrods would be too long, given that's it's accepted the LS7 lifters have the cup .050 higher than stock. But then variables like cam base circle, cyl head milled distance, different head gasket thickness start playing a role.

 

I'm guessing that you'll probably be better with 7.350 or maybe 7.375...

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