Hi

I have a set of L98 aluminium heads (casting 113) on my stock TPI motor from Vette 89. How much can I take off from heads for raise compression ratio without clearance problem between valves and pistons ?

camshaft and valve train it stock...head gaskets are Felpro 7733PT2.

Thanks for help

regards

 

a lot more than you can before you have problems with warpage and leaks

 

is there any markings on heads for limit the milling ?

 

no

 

Only take the minimum amount necessary to ensure a true surface... If you want to raise compression ratio, use different pistons...

 

GM recommends a max .060" flat mill limit for all the small block assembly line heads.
Usually that will get you pretty close to the intake valve seat anyways. Better to deck the block to raise compression ratio and improve quench clearance at the same time.
On a 350 you can achieve way over 12:1 compression using a combination of block decking, head milling and head gasket selection, using flat top pistons. No need for a domed piston.