Anybody run fel-pro 1039 on a 4.500 mega block....The 1039 says its for a 4.590 bore....Is that gonna be to big to work??

I haven't installed it yet, but Nick at Compu-Flow recommended this gasket to me for the 4.5" Mega Block.

They call it 4.590 but if you look at the hole you'll see it's not round. The last thing you want is the gasket overhanging the cylinder bores so I'd say no, it's not to big. I used Cometics on mine last season and didn't really notice the gaskets were overhanging a few thousandths until I tore it apart a couple months back. It was barely noticeable but still there. Could contribute to detination.

BTW, I would not use the Felpros with aluminum heads. The Cometics don't leave an indentation on the head like the Felpros. When I used Felpros with my Indy heads they needed to be resurfaced when the heads cam off.

I'm sure there'll be plenty who disagree but I don't want to put it back together with those grooves on the head surface. Even Brodix says Felpros are acceptable up to 12 to 1 but I won't do it again.

If you are going to use a fel-pro use the 1105 it is a better gasket.

Why you even want to use this FelPro junk? Go with Cometic and you are safe. Price gap is not so big to not choose proper and good quality gasket

I'm using the fel pro 1005 (4.590" gasket bore), these will be .051" thick , had no issues with these gaskets , 500 shot of nitrous to boot.

Just modified the cooling passages in gasket due to the siamese bores.

I have cometics......machine surfaces were prepared perfectly and after taking the heads off from leaking twice on a brand new motor and a can of coppercoat finally got them to stop....

Have never blew a fel-pro gasket ever and never had one to leak so thats why im goin back...And have used them up to 4 times also

Quote((Why you even want to use this FelPro junk? Go with Cometic and you are safe. Price gap is not so big to not choose proper and good quality gasket))

i have never had head gasket problems with the felpros,and i'm always above 13.1 or higher.