All Small Six Cometic copper gasket

[clochard68]

Yesterday I received the copper head gasket I ordered from Cometic. Looks well made.
The gasket cost 67.81$.
Thicker gaskets are available, as far as I know Cometic doesn't offer bigger bore sizes..

Order number: H4287SP4020C
Thickness: 0.020"
Bore diameter: 3.68"

 

[DON]

Is there a different block/head surface finish requirement?

 

[drag-200stang]

What does the instructions say?

 

[Engine Fan]

My experience with copper head gaskets is on a very limited and specific basis, namely high compression race motors. Head gaskets made of copper are often used in racing engines, usually in conjunction with O-rings to contain pressure where the possibility of a blown out gasket is high and potentially catastrophic. I am talking about solid head gaskets specifically, not composition gaskets clad in copper.
Solid copper gaskets will not burn out - which is GOOD.
Solid copper gaskets are hard to seal completely. There often is a small amount of seepage of compression gasses or coolant, which is BAD.
Solid copper gaskets work best when the copper is dead soft. But long term, they tend to work harden, which reduces their seal-ability further. They need to be removed periodically, annealed and cleaned and re-installed. BAD.

The composition gaskets clad in copper would be a better choice over solid copper for a streeter, but I question whether they would compare to the 1024 for pure ability to hold a seal. The 1024 is my go-to gasket for reliability.
Hope this helps.

From the Big Six side.

 

[clochard68]

Is there a different block/head surface finish requirement?

The instruction say 50Ra surface finish is required.

 

[awasson]

This looks like a pretty great solution for the lack of steel gaskets and it brings up the compression ratio of a stock, non-skimmed head back to around 9:1 if the head has about 52cc combustion chamber.

50Ra is pretty standard for aluminum machining (heads) but I don’t know what the Joe average surface finish is for a cast iron block and head. I suppose I’ll find out when I do my large log.

Great find and thanks for sharing.

EDIT: I did read that post from @THE FRENCHTOWN FLYER on the big block discussion. That’s something to consider I suppose. At least the L6 is easier to pull the head off of than the many V8’s I’ve had to replace them on.

 

[John Ha]

Bearing in mind that I'm an oaf, for me that part number (H4287SP4020C) doesn't yield any results when entered in the search box at Cometic.com. I didn't even see any Ford inline 6 cylinder engines listed. Is this a custom, special order part?

 

[THE FRENCHTOWN FLYER]

This looks like a pretty great solution for the lack of steel gaskets and it brings up the compression ratio of a stock, non-skimmed head back to around 9:1 if the head has about 52cc combustion chamber.

50Ra is pretty standard for aluminum machining (heads) but I don’t know what the Joe average surface finish is for a cast iron block and head. I suppose I’ll find out when I do my large log.

Great find and thanks for sharing.

EDIT: I did read that post from @THE FRENCHTOWN FLYER on the big block discussion. That’s something to consider I suppose. At least the L6 is easier to pull the head off of than the many V8’s I’ve had to replace them on.

I tried an MLS gasket on a 300. It failed early on. Admittedly I made my own fire ring embossing dies, but my block machinist said the surface finish on the block deck and the head was way too rough for that type of gasket and that is what caused it to fail. This is anecdotal FWIW, but I trust my very experienced block expert. I went back to the FelPro 1024 rather than re-machining my motors.

 

[clochard68]

Bearing in mind that I'm an oaf, for me that part number (H4287SP4020C) doesn't yield any results when entered in the search box at Cometic.com. I didn't even see any Ford inline 6 cylinder engines listed. Is this a custom, special order part?

View attachment 29432

Yes the gasket is a custom order part!
I just send an email to orders@cometic.com with the part number (which I got some years ago when I made an inquiry for the copper head gasket) and they got back to me very quickly with the cost and shipping.
In my experience they were very customer friendly...