The Stovebolt Site Forums The Shop Area Engine Shop Head gasket seal question

I was wondering what the general feeling is regarding head gasket sealing. Just use a good gasket, use sealant, or a combo of both? What is the verdict?

On my ‘59 235 I used a copper head gasket and Permatex spray a gasket high temperature sealant back in December 2020. So far it’s doing good.

What Phil said x2. You can also use Permatex Aviation Form-A-Gasket if you prefer a paint-on type that will allow you to remove the head gasket later. The copper sandwich head gasket is the best in my opinion by a very long shot.

I have used the copper sandwich gaskets since my first 235 rebuild in 78. When I use them, I always use the copper gasket spray (or years ago it was indian head brush on). I have rebuilt a lot of these style motors over the years, a lot. Never a failure with the copper gaskets.

Recently, I was having an issue with one of my 261 motors. Kept getting a little pressure in the cooling system. My guess was the head had a small crack in it. It was a head I had built in the early 90s (I was a lot younger then, lol) and I was still in my bigger is way better mode and so had ground that head out without mercy. So I rebuilt a new head on the assumption that it was the head that was the problem. I did not want to do the job twice. I looked at my stash of copper head gaskests and decided not to use them.

I opted instead to use a fresh new blue Felpro composite gasket. First time I have used this style gasket. This 261 motor has forged high compression pop up pistons, a very aggresive cam and I have had it as high as 6000 rpm at the race track. No a single issue with the gasket. I did spray the new blue composite gasket with the copper spray-a-gasket.

So I think you will be fine using either gasket type.

So spray/paint one side of the head gasket or both sides?

I have sprayed both sides.

Thanks for the replies. Took the head to the machine shop. Was told it would be 6 weeks. Only 2 guys working there and they are backlogged. Oh well, plenty of other stuff on the truck to do.

I used the Copper spray gasket for the first time a few weeks ago on the recommendation of a friend. I used it to install the intake manifold on my 1966 Olds Toronado. Normally I follow the shop manual to the letter because I like tried and true technology.

In this case I figured there have been a lot of improvements to engine sealing technology in the last 50+ years and it was a lot easier to use than RTV sealer which would have gotten everywhere.

So far no water, exhaust, or oil leaks anywhere.


I used a medium coat on the mating surfaces of the manifold and the heads and a light coat on each side of the valley pan.

Snowman51 On my 48 235 scratched the block and head with at least 320 emery cloth air hosed it put on dry torqued as it shows,ran fine yesterday work done 2 years ago. Old machinist said don't give it any lube,scratched-up surface grips the gasket. Scratched it till block and head were shiny. Learned on big diesel John Deere tractors,surfaces were too smooth.

Snowman 51 I commented on doing head gasket dry. Had a junkyard dog friend who used gun grease on his head gaskets,they worked too. I think if the surfaces are straight it'll work either way,of course higher compression is harder to hold.

dragsix Had forgotten about indian head shellac,water gets under the bridge you know,the place I worked as a teen had it but I don't think we used it on head gaskets mostly fluid type joints.

Sealing compression is a lot easier than sealing coolant. Most composite head gaskets have a built-in coolant sealer on both sides, so adding brush on or spray on sealer is a "belt and suspenders" approach- - - -nice, but probably not necessary. Back when I was using .023" thick steel shim head gaskets to minimize piston-to-head clearance on the zero deck height race engines we built, brush-on Permatex Super 300 was my preferred sealer.

The MOPAR hemi tractor pull engines we built had no head gasket at all- - - -just a copper O ring in a groove around the cylinder machined into the block and brush-on sealer. Of course, the cooling passages were filled with epoxy, and we only ran coolant in the aluminum heads.
Jerry