What is the max valve lift that I can get on an '85 LB9? I'll change the springs out I just want to know how high before my valve meets my piston.

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1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
velcro t-top bag
*****Possible summer '01 mods*****
Wonder Bar from my IROC, 4th gen seats

1985 IROC-Z, TPI Auto
-Accel Super Coil


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You will have a problem with the retainer/locks hitting the guide way before you will hit a piston. It varies from one head to the next, anywhere from .460 to around .500 lift. Only way to know for sure is to check it.

 

I'll second that.

On the GM heads I have worked on, there is no "rule". Some had retainer to guide contact at .460" lift, others would handle 0.480. I am scared by the people who bolt on 1.6 rockers without checking clearances.

TO be safe, measure your heads! I forget, but you need to have a margin, so if 0.460 is max clearance, then you should not go higher than 0.440.

Mark.

 

Thanks I just wanted some idea, I'll check it out when I get there. I just want a little more lift so I probably won't have a problem.