On 2/19/2012, Rich (rwp) wrote:
"When putting on the head gasket on, the only way it will fit is with the copper face up. I thought I had seen some comment that the copper face of the gasket should not be in contact with the alloy head. However I can't see any other way of fitting it!

Neil Burnside wrote:
"Moss produced their gaskets the wrong way up. I bought 3 from them before getting the right one from F W Thornton.

Mick Anderson in Australia wrote:
"The copper side of the Twin Cam head gasket must not be placed against the alloy head. That is why one side of the gasket is copper and the other side is steel. I have attached two photos of a Twin Cam gasket".


NOTICE: The problem has been resolved:
Just a quick review on how such issues should be handled. The first order of business should be to notify the supplier of the problem. They can't fix it if they don't know about it. I notified Moss Motors about this problem 23 Feb 2012. I also did just a little digging, and gave them more detailed information on 29 Feb 2012. On 29 Feb 2012 Moss suspended sales of the part (only 6 days after initial report and on the same day as confirmation of the problem). On 3 Mar 2012 Moss has tossed all of inventory into the dust bin, and has sourced a new supplier to procure good parts in very short order. They also put a stop sales order on Twin Cam head gasket kits with the bad part and will be putting good head gaskets in those kits very quickly. Ditto for the same situation with Moss Europe. In two weeks time the issue is resolved, and your next order will have the good head gasket (as soon as it is available). So don't be shy about reporting any parts problem to the supplier.

More information:
Here is the information I had been gathering for a few days. I have done some research and have communicated with several Twin Cam owners around the world. The pushrod engines had factory issue laminated head gaskets with copper on both sides. The Twin Cam head gasket had copper on bottom and steel on top. At least four people have original issue Twin Cam head gaskets in their possession, some vintage used and some OEM new. They are clearly stamped "TOP" with steel side up.

The factory book "Engineering Technical Data, MGA Twin Cam" (the book no one outside the factory was ever supposed to see) says the Twin Cam head gasket it is copper, steel and clayboard.

Reason for the Twin Cam gasket being steel on the top side is a concern for galvanic corrosion caused by dissimilar metals. The Anodic (galvanic) table of metals has copper and aluminum a long way apart which means high dissimilar metals corrosion. Steel and aluminum are close together on the table which means low dissimilar metals corrosion.

I had second hand information that Moss UK holds in stock a number of Twin Cam "decoke" head gasket kits that have correct "steel on top, copper on bottom" gaskets (but may not have been correct information). Peter Wood also confirmed the gasket should be steel side up, and he sells them in that configuration. A couple people retain used original gaskets removed in the early 60's that are stamped "TOP" on the (rusty) steel side. If the gasket is not marked for top side, you can tell by holes near the front corners that it can only be installed in a single orientation, so you can't turn it over if it is made wrong.

The original MOWOG steel/clayboard/copper gaskets, BMC part number AEH548, were made by Payen. Stamped impression in the gasket is quite faint. It shows "Payen" and a part number that looks like "1A827" It cross references to Payen part number AD850. They likely have the drawings so they might on request make them in the modern material. The black fiber stuff would probably be nice, as it seems to be bullet-proof in the pushrod engines, and has no galvanic problems (being non-conductive). The eyelets around some of the holes are metallic and might have galvanic corrosion problems with the aluminum cylinder head.

Here are pictures of an original used head gasket, slightly corroded but with all stamped lettering clearly visible. Gasket supplied by Bob West. Photos compliments of Michael Pratt from Moss-Europe.



Further to this, Mick Anderson in Australia wrote:
"My gasket would be from when the factory built the car. I removed it in 1964 and that was the first time the engine had been apart. On the gasket are the following markings".
On the copper side:
    Payen 1A827
    MOWOG
    AEH548
    Made in England
    A
On the steel side there is only the word:
    TOP