Undersized club supplied copper head gaskets

[Rob Harknett]

The parts service have been advised and despite having sold numerous gaskets from this batch over the years have withdrawn them from sale. However whilst it easy to say get some more thicker ones made, it's not so easy to do.

As Rob said above they have been withdrawn and a new supplier as been found. Its a shame to have to scrap them they were bought from a Club member
a few years ago so no chance of a refund.

If the old gaskets were really only half the thickness. Some members may be prepared to accept them 2 for the price of one. They have been used for years without too many complaints. WHY? Perhaps because wear & tear in other areas, made the thinner gaskets just what was needed. The new correct thickness gaskets will now double that wear & tear. This seems to be proved re the comment something had to be shortened. Had that part been worn, it would not need shortening. Nothing will be 100% correct unless everything related to it is also correct. e.g as 100/ 30 year old type petrol is no longer available, correct spark plugs, carburation and valve seats are no longer best suited or available. So perhaps those thinner gaskets are just what a worn engine wants.

[clive]

Rob i cannot work out how wear would result in the thinner gasket being better. If the head has been skimmed then a thicker gasket is needed to prevent the head locking down on the barrel spiggot. I had to get the recess in heads on my G11CS machined a little deeper to compensate.

[Groily]

I don't know how thick they were or weren't, but the problem with 'too thin' isn't anything that could normally usefully compensate for wear and tear.
It's about the spigot on the barrel/head joint: too thin and the gasket isn't compressed before metal hits metal.
The spigots can be milled down a bit or grooves deepened (got the T shirt for that), or whatever - but many people wouldn't want to do a bodge to get round a part problem in that way, preferring to have the correct part.
I think there are threads here and there on the forum about thicknesses - from memory, you need about 70 thou to be safe. I've seen gaskets, composites as well, that are in the 50s, and they can't /don't do the job safely absent attacking the castings.
With the copper ones, little o rings in the rocker oil feed holes are generally a good idea, or at least it's what I fitted, as they came with. But all they can do is help prevent oil leaks - compression leaks are guaranted if the gasket fit is sloppy, and will soon blow the oil out as well, whatever has been used.
Worth ensuring, also, that there is NO OVERLAP of the gaskets between the cylinders and that all the holes are neatly finished (no raised edges), for studs, oil passages and above all the pushrods. Any fretting there can kill a pushrod over time - got the T shirt for that too. Plus, the instructions about not doing up the inlet manifold tight until the heads are on properly are very worth following.

Just seen Clive says pretty much the same thing . .; so +1 for that

[ajscomboman]

Up until very recently it's been impossible to find another supplier of these gaskets, however now that there is one and we've been made aware new stock has been ordered and the old discarded. Hopefully they'll be with us in a week or so.

[Rob Harknett]

Rob i cannot work out how wear would result in the thinner gasket being better. If the head has been skimmed then a thicker gasket is needed to prevent the head locking down on the barrel spiggot. I had to get the recess in heads on my G11CS machined a little deeper to compensate.

I am not aware of all the if's and buts related to a twin head gasket Clive. Usually something bigger is used to take up wear in something. There are times when something smaller results in a fix. But that is usually like when I buy something that is too big for me to wear. I just give to Jan to wash and it ends up my size.