came up on a good deal for a 347. with my afr 185 58cc this short block would yeild me a 10.8-1 compression. I might be able to exchange my heads for some 64cc which would give me 10-1. If I am unable to exchange the heads what are pros and cons of running 10.8? Any other way to lower it a touch?

Thanks
Dan

 

Fel Pro 1011-1 gaskets would help. They're an extra .002" thicker than the -2 gaskets. I bet you could get away with pump gas if it's tuned properly. Those heads have CNC'd chambers, so there aren't any rough casting surfaces to heat up and cause preignition issues.

 

i run close to 11.5-1 on the street and havent had any problems

 

i wouldn't know. my head would just say go for it go for it

 

I agree with Kalli!

 

Kalli...LMAO..I agree

Starfury--how much would a gasket help? 1011-1 are the gaskets I have for my heads

 

Kalli...LMAO..I agree

Starfury--how much would a gasket help? 1011-2 are the gaskets I have for my heads

 

Cometic makes head gaskets in different thicknesses. I have a 4.6 in my 65. The stock/Felpro gaskets are .039". I'm using .062" Cometic to lower my compression. It amounts to about 1/2 a point on my motor (11:1 to 10.5:1).

 

The 1011-1 gaskets are .041", whereas the 1011-2 gaskets are .039". Both have a 4.100" bore. I'd have to know piston dish volume and how far they sit down in the bores to be able to accurately calculate it, but it's not going to be a whole lot. Maybe a tenth of a point or two. Those Cometic gaskets may be the way to go.

 

What compression you tolerate on pump gas has a lot to do with the cam, intake and head selection.

And don't lower compression by using thicker gaskets, it just makes the problem worse. Yeah, you might lower compression by a half a point, but you reduce quench effectiveness which reduces detonation resistance.