Until I took the head off this year I never had a problem with leaks at the rocker feed banjos, but now I can't stop it leaking. I've tried fixing it about half a dozen times, and even scrupulous cleaning of all the mating surfaces and fitting new fibre washers and bolts, (the threads were worn on the old ones) it still leaks. I managed to get it so that only one leaked, but both have to come off together and on reassembly they both leaked.
What am I doing wrong?
I had a devil of a job fixing leaks from the rocker feeds on my B32. It was bad enough when I had the iron engine in it but far worse when I put the alloy top end on it. The original fitment had taper to taper joints between the banjo and the rocker spindles as well as taper to taper joints between the banjo and the banjo bolts. The taper faces of the spindles were pitted from corrosion as the head had been stored in damp conditions for many years. So I fitted the later spectacle type banjos which mate against the cylinder head face with a fibre (or Dowty) washer to seal that joint. But still got leaks from the taper banjo bolts.
The fix was to make new banjo bolts with a standard head and a flat underside surface. With soft copper washers under the heads of these banjos the leaks were finally cured.
Derek has suggested a good solution of using annealed copper washers between the banjo and head. If you google the BSA part number for the Banjo to Head washers (31-8430) you mainly see the red vulcanised type which in my experience are not very good for sealing against oil leaks on Beezers, but are excellent for use in water systems and they have a max temperature rating of around 120C. So, make sure the mating surfaces are as flat and clean as possible and use copper washers. Also you may find that the angle of taper on the banjo bolts may not exactly match the banjo so observe this area and rectify accordingly. HTH
Thank you Derek and Ian.
Copper washers it is, at least under the banjos. I'll try lapping in the banjo bolts with the banjos, and if that doesn't work, I have a mate with a lathe who might be able to help me. I don't think he can make a hexagon head, so perhaps getting a couple of hex headed bolts with the right thread and drilling a hole up the middle (and a cross drilling too, of course) will do the job; ending up with copper washers sealing both sides of the banjos.