Thanks for that both of you. It's some 48 years since I last took an M21 apart [ at boarding school where we hid it in a teacher's garage]. I have a much clearer idea of what the options are now. The engine was rebuilt fairly recently so may be I won't have to pull the engine out. Cheers.
I had thought about that, we'll see how the stud moves. Probably won't deal with it till Easter as I have just started working again after twelve weeks off with a spinal problem and so am way behind on my orders.
Well I finally got round to fixing it. Stud came out easily. The reason I overtightened was due to the magdyno wobbling on it's central underside bulge so It was suggested that I cut out some gasket sheet and place it under the mag. With an extra strip under the points end it lined up properly within the seal so no more blow by out of the mag drive housing. Then I found that the points block thread was no more, actually I don't think there's been any thread there during my entire ownership. An engineer mate tapped the ally with a punch to tighten the ally onto the threads, that held for 80ish miles.Now it's loose again. Another engineer at a vintage show said he had a good one for a fiver, so I'm picking that up tomorrow.
However the selfsame engineer noticed that the magdyno clutch endplate screws were loose on my 16H, and that no grease appeared to be escaping so suggested I take off the magdyno [again] to regrease and tighten. It's an easy job [a lot easier than trying to relocate the new magdyno strap on the M21]; with socket sets one doesn't need to take off the cam housing despite what the manuals say. You don't need to retime either if you mark the points cover and fix it back in the same place. It just takes time. Still I have never taken off that end of the magdyno. Has anyone experience of just how much grease one should pack in there?
Very little grease is required for the fibre gear and it may well have enough in there. It certainly does not require to be 'packed' with grease..The easy solution would be to loosen the mag and dynamo straps and slide back the dynamo from the magneto enough to give access to the fibre gear teeth. After retightening the mag straps, apply a little grease to the gear teeth through the resulting hole, turning the engine slowly to access all the teeth...
Regarding the thread in the point block I'm assuming you mean the fixed point...If so you can fit the point from a K2F twin cylinder mag which is a larger diameter...Just drill and tap the block to the correct thread...The K2F point is also slightly longer so it will need to be shortened to match the magdyno point before fitting....Ian
Thank you very very much Ian. I really appreciate this. One point though, on the 16H the mag is bolted to a platform so just the one dyno strap. I can slide out the dyno and just apply a bit of grease to the gear; or do I need to drop in a bit to lubricate the clutch; or is the clutch supposed to run largely dry?
I think I can live with one shrouded retaining screw remaining possibly loose, it's not going anywhere.
I picked up the magdyno clutch housing gasket from Dave Lindsley. He said he helicoils in the correct standard thread and charges £15. He said I'd done well to get the points block for a fiver as one of his customers had paid £50, though not from him. I'm lucky to have him on my doorstep as I've found him excellent and extremely helpful. He does have a long waiting list though, about 5 months.
