How much lift can aluminum L98 vette heads take?

 

.500

 

I ran the TPIS ZZ-9 cam with a 1.6 rocker on the intakes with my 'vette heads and the lift was .520/.520 with no clearance issues.

 

Its not just clearance issues you have to worry about, but what the springs are made to handle. If you put in a cam with too much lift for the springs, a spring could break. Which would be bad.

You might get away with it, but you might now.

I would think they are made to handle about .460-.500 safely.

 

Just have the heads reworked to handle the lift. My heads could handle the lift but I decided to go for a better spring package.

 

I've used the LT4 Hot Cam Kit which gives .525" of lift. This was with over size valves on a ZZ4 short block, with no clearence issues.

 

But this is an L98 not an LT4 so I don't think it is the same thing.

 

You are right. I also used a set of Comp Cams conical shaped valve springs to cope with the extra lift. No need to machine the spring perches.

 

Well, if you go that way, I suppose you would be fine to go as high as the spring will allow and the piston doesn't hit the valve.

 

K-Motion makes the K700 or K750 springs that fit that head and give over 300 lbs of open pressure and about 135 lbs on seat. I used those with a roller on those heads. They fit the stock spring pockets. A good choice if you need more spring pressure on those heads.

 

This was on an L98 with the aluminum heads. The LT4 Hot Cam Kit can be use on earlier roller cam. SB's.
Sorry i didn't make that clear.
I used stock L98 aluminum heads, had them machined for over sized valves, the LT4 springs, pocket ported and port matched to the intake.
As I said there were no clearence issues with the rated .525 lift. So I see no reason that the L98 could not support higher lift cams.

P.S. The engine produced 401rwhp.