Anyone heard of an 83mm "steel headgasket or were

[karls59tr]

Anyone heard of an 83mm "steel headgasket or were

all steel headgaskets 87/88mm? Also Moss says their Corgasyl steel head gasket is for lower compression engines. I thought a steel headgasket would raise compression? Or are they two different headgaskets? One is a "Corgasyl Steel" head gasket and the other is just referred to as a Shim steel" headgasket?

 

[Twosheds]

Re: Anyone heard of an 83mm "steel headgasket or were

Also Moss says their Corgasyl steel head gasket is for lower compression engines.

For use on lower compression engines or...

to lower the compression of an engine?

 

[TR3driver]

Re: Anyone heard of an 83mm "steel headgasket or were

The original "shim" steel head gaskets were part of a "compression lowering kit", P/N 502227, intended for use in countries where high octane fuel was not available. The kit also included a thicker steel spacer and longer pushrods. Installing both gaskets plus the spacer (which ISTR was something like 1/8" tall) lowered compression considerably.

Then some smart guy (probably Kas Kastner) figured out that the "shim" steel gasket used alone (in place of the stock composition head gasket) would boost the compression ratio a bit, giving a bit more 'oomph' in racing.

I believe the factory steel gaskets (202275) were big enough to use with 86mm bores (they are listed for both 83mm and 86mm low compression kits in the TR4 SPC). However, since they are only formed sheet steel, it's trivial to cut away part of the gasket, allowing for larger bores and even relieving the bore around the intake valve (which I believe was another Kastner trick). As I recall, the gasket I got from BFE (which probably came from Moss) had to be trimmed to not protrude into my 87mm bores.

FWIW, I have an early TR3 short block where the pistons will kiss the head with a shim steel head gasket installed. If you are considering installing one, it might be wise to check the deck height. It might be just coincidence that I got two blocks in a row that weren't machined just right, but I am guessing there are more around.

 

[Darrell_Walker]

Re: Anyone heard of an 83mm "steel headgasket or were

FWIW, I have an early TR3 short block where the pistons will kiss the head with a shim steel head gasket installed. If you are considering installing one, it might be wise to check the deck height. It might be just coincidence that I got two blocks in a row that weren't machined just right, but I am guessing there are more around.

And allow for the fact that the rods stretch a bit once the engine is spinning.

I purchased a solid copper head gasket from Gasketworks for a mild bump in CR. Mordy Dunst recommended the 0.032" as the thinnest I should go with stock rods, even though he also carries a 0.022".

-Darrell

 

[karls59tr]

Re: Anyone heard of an 83mm "steel headgasket or were

Randall What method is used to trim out an 83mm gasket to 87mm?

 

[TR3driver]

Re: Anyone heard of an 83mm "steel headgasket or were

Seems like I used an abrasive burr mounted in a Dremel, but I don't recall for sure. It was whatever Ken G. suggested.

Or check in the "Competition Preparation Guide", I think it had a suggestion as well.

 

[Darrell_Walker]

Re: Anyone heard of an 83mm "steel headgasket or were

For my copper gasket, I used a sanding drum in a drill press (this was to clear the area around the intake valve).