carb to head gasket

[David Tinsley]

1955 A10 GF

Looking at the parts book it lists 3 gaskets (65-1232) between the carb, drip tray and head (iron head).
I can see how I need two, one either side of the drip tray, but cannot figure where the other one is used? Are two of them maybe doubled up? If so on what  joint, drip tray to head, or drip tray to carb?

Also, on the same subject, I was surprised not to see a thick tufnol gasket between carb and head listed for heat reasons. All the unit singles and twins I owned had one. Is one not needed on the A10, or was one not considered in the 1950s and mabye I should add one between drip tray and head?

Thanks in advance for any ideas. 

[bikerbob]

The tufnel gasket is listed for the alloy heads 65-1419 called a distance washer not listed for the iron heads so the alloy heads will need 3 gaskets but the iron heads will only need 2. My 1956 A7 does not have the tufnel gasket but I had a 1957 A10 some years ago and it had that tufnel gasket, but maybe a previous owner fitted it for some reason. My A7 has the original air filter fitted which is a tight fit as it is but if I had the tufnel washer fitted I am not sure if I would get the air filter to fit it would make it very difficult.

[David Tinsley]

The tufnel gasket is listed for the alloy heads 65-1419 called a distance washer not listed for the iron heads so the alloy heads will need 3 gaskets but the iron heads will only need 2. My 1956 A7 does not have the tufnel gasket but I had a 1957 A10 some years ago and it had that tufnel gasket, but maybe a previous owner fitted it for some reason. My A7 has the original air filter fitted which is a tight fit as it is but if I had the tufnel washer fitted I am not sure if I would get the air filter to fit it would make it very difficult.

Thank you, it all makes sense now.

[Azubi]

Are there any typical symptoms that you can (try to) improve with a tufnel gasket? I assume hard to start when hot?

[bikerbob]

That was the whole idea of the tufnel gasket to insulate the carb from the head, but it can help  to cure a possible  imbalance where one cylinder may be running richer than the other you can then make the tufnel into a wedge shape and divert more mixture to the leaner side. I did this on an A10 Gold Flash some years ago.

[Colsbeeza]

Hi David,
Some reading here you may be interested in on induction bias gaskets.

https://www.a7a10.net/forum/index.php?topic=7720.0

Col

[Black Sheep]

My plunger A7 has a very thin, 1/16" tufnol gasket between the head and the carb. To the best of my knowledge, this is what was fitted to the plunger engines. My A7 was totally original when I first got it so it's a pretty fair reference. I've just fitted new rings at last. No more puffs of smoke on accelerating.