With the nuts and tab washer reassembled correctly and also with the spring cup being tapped gently into place I now only have only one spare thread showing. The inside of the chain case has had its weld high points ground down and all was reassembled.
It started first kick (they all do that sir) and I did notice that the primary case dome became warm instantly but with no noise. I think that there might have been the slightest contact at first but it all seems to be ok now.
I did notice that the clutch basket is quite slotted so I will look for a 'new old stock' item to replace it.
Today I've had several rides through the Devon countryside up and down hills and nothing has blown up. The new piston and valves are all swishing away like a Swiss watch and apart from the need for a little clutch adjustment the whole plot seems very happy with itself. Brakes are very powerful, the handling and steering are very natural and the overhauled charging system and magneto are all spot on.
The photo Feked have for the 'Ariel heavyweight' clutch centre is for the 5-plate 350 clutch. The photo on the 'Panther heavyweight' centre looks more like the one for the 7-plate 500 clutch. Have they just got the photos mixed up 'or what'.....
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)
A couple of hours in the saddle to Appledore and back in torrential rain and nothing went wrong. Hurrah again!
On strange thing... the clutch center was running off kilter. I removed it and re-assembled. It's a mystery that something which fits straight onto deep splines could ever be 'off'. Anyway, the clutch is much improved and lifts almost square now.
Note to myself : Never tickle the carb after a lunch stop when the engine is still warm.