XYute

Can anyone tell me if I can get 11.5-1 cr with flat top pistons
and 4V closed chamber heads?

Xtreme F6

yer you can but you will have to deck them down a fair way and on the edge of the heads where the big water jacket is they get thin and tend to leak water. Just run a 0 deck and see how many cc you have in your heads tell me and ill work it out if u need a hand. also the cc of the piston valve reliefs

xacoupe

Std 4V CC give you 10.5-11 anyway. It's a lot of work for not much. If you are going to run AV Gas or whatever you may as well run 12.5 or so and go beserk with the motor

I8AHSV

I agree with what xacoupe said... I think the most you can run on premium unleaded petrol like Mobil Synergy or Optimax is 11 to 1 and that's with a big solid cam... and even then I think you might need some sort of a octane booster.

qwikcorty

anyone know how many cc's the std valve reliefs are?

__________________
1976 351c td cortina

RevHeadRon

so what sorta compression ratio would you get with 302 heads on a 351 motor?

brenx

I can't remember seeing a stock domed valve?? I've seen aftermarket domed valves. Usually the valve relief is 1-2cc's.

REVHEADRON: At least 11:1 with 302 closed chamber heads.

Brenden

__________________
XB Fairmont (street car) 11.07@123.02mph.

Xtreme F6

Um you guys way off here. Std 4v closed chamber heads 68 cc. The valves reliefs in a flat top trw foe example are 3 cc each

Racer

It's been a long while, but from memory the chambers on my old phase 3 were 62 or 63 cc, and that was after polishing. What figures here???

As Maniac said, aftermarket pistons usually figure around 5cc or 6 cc, so i'd guess 4 or 5 cc for a standard piston.

Xtreme F6

Ive had 4vs down as low as 56 cc but like isaid they get real thin on the water jackets at the end of the heads so try avoid it.