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.
Last edited by Dragsix; 10/05/2021 1:57 PM.
