Fitting New Carb

[Howard]

I brought an Amal Concentric Carb for my `51 A7. The carb came with an "O" ring that fits in the carb flange however  originally the bike had a gasket between the head and carb. Should I use the o ring set up or a gasket ? 

[MG]

I'm using a 930 Conc. on the Flash with a 3mm thick Tufnol spacer as a heat barrier AND the O-ring on the carb. No leaks at all with this setup.

Cheers, Markus

[Goldy]

If it,s got an O ring then you don,t need a gasket, but as MG says the tufnol gasket is very good for preventing heat transfer to the carb which prevents all sorts of odd running faults.

[BSA_54A10]

I toss the O rings as well but I use a thick soft gasket which will compress and partially fill the hole where the O ring went.
Most important is how tight you do it up.
When done up correctly you should just be able to twist it a bit on the mounts ( allows for expansion )

[iansoady]

That's right, many people do them up far too tight. I always use single coil spring washers and do them up so the washer is just compressed.

I also use the thin gaskets between tufnol spacer / drip shield and drip shield / head joint, with a light smear of grease.

[Howard]

Thanks all....regards Howard