I am replacing the headgaskets on a 502 efi mag what sealer should I use on the headgasket to ensure a good seal?

None !

Modern head gaskets have thier own coatings that seal them while allowing them to move as the heads and block expand and contract.

Bill Koustenis
Advanced Automotive Machine
Waldorf md

Yes. And only use a marine head gasket. Fel Pro makes an excellent one. make sure you follow the retorquing instructions or you'll be disassembling your new engine again- very shortly.

Personally, I Like Cometic headgaskets. A bit more $$, but worth it. No need to retorque them.

I've got a mild build 502 mag efi that has leaking head gaskets. Only 80 hrs. Built by Baker Eng. I know the heads were never retorqued. Is that why their leaking, who knows. Put me out of a boat for the summer though.

No sealant as Bill K said.


Could be. Fel-pro's don't need retorqued after a heat cycle. They get retorqued upon the initial install. Torque all head bolts in proper order and then loosen each bolt one at a time and re-torque it.

They put a little paper slip in every package that details the procedure. I'll see if I can dig thru the trash and I'll post it.

This is the marine gasket- I have no idea about their automotive gaskets.

Felpro MLS gaskets are like flypaper. They'll stick to the wall!

What I posted is what came on the directions in my felpro marine gaskets related to the need to retorque.

I'm going to have to dig that slip out. Maybe a recent change?