i just wanted to ask some of the gurus on here some advise that ive been scratching my head about lately.

i have a set of world heads (200cc intake runner and 66cc combustion chamber)

these heads are going on a stock l98 bottom end with a fully ported TPI intake and a comp xr270 cam.

what i was wondering was how much will my compression change going from a 64cc head to a 66cc head. will i notice the drop in compression? would getting them milled down be worth the money?

im not looking for a " sell those heads and buy afr's " answer im looking for a cost effective answer.

Thanks guys

 

2cc isnt going to matter all that much. Just run them, forget milling. Use a head gasket near stock thickness to avoid any more loss of compression.

 

ive got a thinner headgasket than stock to make up for it. thanks for the comment.

 

Good. i was going to say that with a 270degree cam, you don't want to drop compression too much below stock. The L98 was stated at 9.5 CR actually closer to 9.2. You want to be 9.5 or better to assure good low rpm drivability.

BTW, in answer to your original question, I believe that Comp Cams has a CR calculator on their website.

 

With stock deck height in your short block, I'd go with the Felpro .015" head gasket (search for it on www.summitracing.com ). It will improve (tighten) the quench clearance for better performance and detonation resistance, and give you the much needed compression boost for that cam.