I'm thinking to use Cometic C5645-040 head gaskets for my forged low compression FI engine.

They are saying at Cometic web site, that a surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.

I have new AFR 195 cc SBC LT4 eliminator street heads and the block will be resurfaced. Do I need to do something to those heads?

 

I'd ask AFR what they finish them to if you don't have access to a "profilometer" as I think it's called. Ditto for the block deck. They aren't kidding about the surface needing to be smooth and flat. They WILL leak if it is not.

Rich

 

So, if not Cometic. What do you prefer?

 

There are are agreat choice, but the prep has to be right or don't bother.

Rich

 

Depends on the boost level you're looking to run. I have heard (no personal experience) that FelPros 1074s IIRC are good for low boost apps. For higher boost, the SCE Titan gaskets. I'm running Cometics, but I had my cyl. heads and block decked so the surface should be good.

 

I'm looking 15 psi boost level. Is that FelPro 1074 enough for that?

 

What do you consider LOW boost?

I have been running Fel-Pro 1074's for years and have never had a failure at over 24 lbs of Boost.

 

I never said the Felpros wouldn't work. I just have no experience with them. My engine builder recommended the Cometics over the FelPros as he felt they had superior sealing given the right surface finish. Of course, if you're running a cyl. head with a thicker deck (AFR), you should have less problems sealing.

 

all you need to do is coat both sides of the gasket with the copper spray and you wont have any problems

 

My new LT4 stroker was built with cometic head gaskets. I was told they are pretty much bullet proof. AFR Heads were also used in the build.

 

Yes, they will be fine. Ive been running the 1074s for years now and never had a problem. My friends running 20+# of boost with the 1074s.

 

awesome gaskets, im running the .030 thick ones. Put on my heads straight from trickflow and they leaked, had to pull them and have them milled...reused the same gaskets (they are reusable) and no leaks yet, 14psi on twin 70mm turbos, 8.4:1 compression.