[Fot] Help with 89mm head gasket

[Philip Gott]

Merry Christmas!
The composite gasket can not be cut back.
The steel shim gasket can -and must be cut back as you describe.  Best to err on the side of taking too much off rather then not enough. We have had good luck using (and re-using) these with Hylomar.  The cylinder liners should protrude above the block .005 to .007 or the seal will be “iffy.”
Phil Gott

Sent from my iPhone

> On Dec 22, 2024, at 11:30 PM, Greg Blake via Fot <fot at autox.team.net> wrote:
> 
> So I’m building my first 89mm motor. Before you flame me, it’s a hot street motor.
> 
> The head has been skimmed enough to remove the intake shroud. I have a Lucas brand big bore head gasket. It is a composite gasket with a steel fire ring. That fire ring hangs into the combustion chamber all around the intake valve. I don’t know if that Lucas gasket can be trimmed or otherwise modified to be able to work with this combination. So that’s question one.
> 
> I also have a bunch of old stock steel shim head gaskets. The pictures below are of that gasket sitting on the head on the work bench. You can see it hangs into the combustion chamber as well but only about 0.010”. It’s the piece of metal that is inside of the fire ring. It looks like I could easily trim that with a flap wheel and have no part of the gasket in the combustion chamber. So that’s question number two. Is that the remedy for the shim steel gasket.
> 
> Last question. I’ve never used a shim steel. Do I still go for 3-5 thou protrusion and then coat with copper coat?
> 
> Thanks folks and merry Christmas 🎁
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