Blanking plug fell off into magneto chaincase bottom half

[56G80S]

Just for amusement value. Returning from short run heard a whirring sound from mag chaincase.

Popped it off and a small round dished disc fell out together with oily grease.

It was the blaming plug where the inlet cam is.

Tempted to just stuff it back in with some loctite but won't. So it's cambox off and inspection tomorrow.

Bet there's quite a bit of end float.

Johnny B

[56G80S]

So it's not just for amusement.

I've checked out lots of posts on camwheels. The endfloat on the camwheels is 25 thou inlet and 31 thou exhaust. I checked this my usual way, electricians (very soft) solder, put the cambox back on and measure resulting solder thickness with vernier.

Question is, what should I put it at? I don't use a paper gasket on the cases as the fit is good and Welseal does the job. Would 5 thou be too much? Planned to shim but revised that to warming the cases and tapping the bushes as appears to be usual practice after reading the posts.

Stop here and respond unless you've nothing else to do, in which case, a longer story follows.

I also found some witness marks on the case where the mag shaft enters as if the chain had just barely caught the case. This was probably due to my naughtiness as I saw ages ago that the ring between the case and the mag was soft / failing. I know I had a new one somewhere but couldn't find it so as I was setting off for Poland I put a cable tie round it. And then forgot all about it in the wake of other events.

I think it pressed the casing outwards. Odd thing is I found the new ring and it's way too thick, about 0.63 inches versus a gap of 0.44.Suppose I could just cut it but difficult to get a straight cut. I will fit the new Regina chain that I bought and didn't fit about 8,000 miles ago. There's now noticeable wear in the Renolds that has been on since the mid 70's and that's while it's still got grease; cleaned and dried it would be more.

Will set to 350 valve timing while I'm on, both camwheels are H with three dots. I've found another exhaust cam with no marking and very much like the H that's in use. It's got two official dots and one that looks "homemade". Wish I could find the SH, it's there somewhere.

Last laugh is, I wondered why there were scratch marks on a tooth on the half time pinion. I realise now I'd done that so long ago I forgot - there's no dot on the pinion! Spent quite a while kneeling down looking for it before I realised though. It sits straight up on TDC.

Johnny B

[raffles]

John although many folk tap the cam bushes back I have found the overtime they can and have done on my own 56G80
creep back to their original position. This being the case I now always shim them (shims are available from the club)
Tony

[56G80S]

Tony

Thanks. I have some shim stock that I can use to make up shims but what I don't know is how much play to leave!

At least you've saved me from the bush shifting error. It also now occurs to me that shifting the bushes would be very imprecise.

Johnny B

[Braaap]

One or two thous of an inch should be plenty of clearance. In service the ali cases will grow off the cam.

[56G80S]

Thanks for the advice. Just need to sort out the slightly sticke auto AR unit first (again) and will crack on.

Johnny B