rocker box leak

[a101960]

Copper gaskets are good, but for a really effective seal they need to be used with 3 bond. Mine always leaked fom the L/H exhaust valve area, and the reason for this is that at that point the cover and head surfaces do not line up very well. They are slightly out of alignment so subsequently it is not a good match in that area. I tried many times to get a good seal without success. It would be OK for a while before it started to weep and then getting progresivley worse. Copper gaskets with 3 bond have thankfully resolved the issue.

[CheeserBeezer]

Halfords sell a Loctite product ref: MR5922 (from memory) in a white 'toothpaste' tube. This is the best gasket paste I've ever used for conventional joints. I find with rocker boxes it is necessary to flat the surfaces, use good quality gaskets that aren't too thick and tighten the box down very tightly, then go back and retighten. The problems are that the pushrods and valve springs are trying to lift the rocker box off the head, the head steady is vibrating the rocker box on the head, and generally it's not one of BSA's finest designs. Coupled with the fact that it is difficult to fit without smudging the paste and damaging the gaskets we're up against it! However, using the above I've managed to get (most of!) my rocker boxes reasonably leak free.