What is the max lift that a stock iron head L98 can handle before threre are valve/piston clearance issues? I know the duration of the cam is an issue, but I just need a rough idea. I've got KB flat top pistons and iron heads that haven't been decked.

 

oops

 

oops sorry..

 

the stock retainers hit the valve guide at around .480 or somewhere close i believe.

 

I'm looking for max lift before there are valve to piston clearance issues. How much lift can I have before the valves hit the pistons? I've already had the guides cut down enough so the heads will handle .550". Before I had them machined, the stock heads would only handle .435" before the stock retainers hit the guides. So all the stuff I've heard about the stock heads handling .480 is a bunch of .

 

I installed a cam with these specs using stock L03 heads on a TBI 305:

217/225 @ .050, .475/.480 lift 109 LCA.

I was using Comp Cams Magnum rockers with 1.6 ratio so my overall lift was in the low .500s. That was on stock springs and after about 2000 trouble free miles I installed Comp Cams conical springs and locks and retainers -- supposedly good for .550 lift.

I never noticed any difference after installing the new springs I just put them in because the guy at the local speed shop was freaking on me running that much lift with stock springs.

adious,
RP.

 

Nasty_Bird_'90 did you ever find the min clearance needed? i needed to know the same thing

 

I ran a ZZ4 cam in an 88 l98 IROC , no problems for 10,000 miles . Engine and heads were totally stock . Intake lift is .510 . I don't know if this helps you . Probably not .