Six weeks into ownership of my 1954 A10 and I have tackled leaking rocker box, leaking petrol taps and duff front brake. I didn't think in time to take the most important pictures, of the cyl. head facing and the rocker box facing surfaces ... both were poor, and the gasket showed where the oil had been exiting in the inner side of both exhaust valves. I cleaned and levelled the rocker box faces with a very good and fine file and used cotton buds dipped in grease + good torch to remove filings. I degreased and cleaned the cylinder head facing and used loctite 5920 on one side of the gasket. I had to do that twice ... first time, despite what i thought was great care, I was surprised how much squeezed out inside the rocker box so it all had to come off for a second attempt with much less sealant. So far, 50 miles in at a steady 60mph, so good!
I had an issue with studs: I adjusted the valve clearances a few days after collecting the bike and thought I had stripped the thread on the top exhaust side cover stud so I bought one from one of the big BSA parts suppliers. It is stud A in the picture. It turned out that the thread had stripped in the rocker box and the stud was in poor condition so I had a helicoil fitted and the engineer made a new stud - B in the picture, because the unthreaded portion of the supplier's stud was actually thicker than the box cover so would have been impossible to tighten down. I spoke to the supplier about this but the reply seemed to be that "we have got lots of studs and they are all like that" which isn't too good.
Petrol taps have been replaced with ethanol-proof versions and the garage smells sweet again. The front brake is much improved after dismantling, cleaning and a bit of work with fine abrasive. Although there is a lot of liner still on the shoe, the angle of the operating arm tells me they need relining. Thanks to everyone whose postings turned up on searches with advice on these matters.
