1958 model 30 magneto

Ironhead · Post by **Ironhead** » Mon Jul 13, 2009 9:51 pm

Thanks to everybody for all the advice, I think I will get mine restored the body is OK going the auto advanced way looks rather complicated for me
Thanks Alex.

itma · Post by **itma** » Mon Jul 13, 2009 10:24 pm

why cant you buy the auto advance magneto and just swap over the necessary bits at the points end?
But getting the one you already have properly sorted is the only sensible and economic way.

Tolly · Post by **Tolly** » Mon Jul 13, 2009 10:45 pm

Don, are you saying that all AMC twins had manual adv/ret? If so I'm now getting a bit worried as the drive gear, all be it NOS, came from a third party through a friend.

Don Madden · Post by **Don Madden** » Tue Jul 14, 2009 3:44 am

I have seen a lot of twins, especially the 1955-up but never seen an autoadvance for one. The best source of info for any electrics is the Lucas Spares manual & they list only manual advance for the seven different magnetos fitted to AMC twins. The 1958 Moder 30/G11 was fitted with the 42264A manual advance unit.

But if the gear on the AA unit is an exact match for the intermediate, I see no reason not to use it.

Cheers, Don.

Tolly · Post by **Tolly** » Wed Jul 15, 2009 3:57 pm

I must first apologise to Ironhead for taking over his thread.

Thanks Don, I don't know the manufacturer of my auto drive gear so I can only assume that someone changed the mag and used the original fixed gear, I then came along and wanted to perfect the running so obtained an auto drive gear.
This has opened a can of worms for me as I took the timing case off this morning to photograph the gears and found there was too much play in the mag bearing for my liking, it looks now if I have to renew it, anyone know the best place to get mag bearings?
I have posted a couple of photo's in the postwar twin parts section, they should come up in a few day's. One is to show Wilko the adv/ret mechanism and the other is for anyone's comments on the gear meshing, although it doesn't look too bad to me.
Don, the number on the mag is K2F 42378D, is there any way of identifying that please.

Don Madden · Post by **Don Madden** » Wed Jul 15, 2009 5:11 pm

The 1936-1959 Lucas spares manuals have a cross reference of spares numbers to usage but I do not find the 42378D listed. 1960-up do not have a cross reference chart. I was unable to get more information. Sorry.
Cheers, Don.

GSAX1 · Post by **GSAX1** » Wed Jul 15, 2009 9:20 pm

Tolly: the problem with too much mag bearing play could be rectified by shimming the mag correctly. Either remove some of the brass shims (if present) between the body and the points housing, or add shims behind the armature inner races. Beware that the races are difficult to remove and you will need a special bearing puller.

However the problem is more likely that the outer bearing races are loose within the paper cups that insulate them from the mag body. A common fault. The paper cups are available in several oversizes, but the front one is a pig to change. You will have to manufacture a special dowel. Buy two of each cups, as you are bound to destroy one.

Good luck.

Michael

Tolly · Post by **Tolly** » Wed Jul 15, 2009 10:43 pm

Thanks Michael, from what you are saying the bearings are a tapered type are they?
I will look in the repair manual as I have not gone that far yet.

wilko · Post by **wilko** » Thu Jul 16, 2009 12:30 am

While you have the timing cover off you'll notice why they wetsump.If you're bored you can watch the oil slowly trickle out and around the spindles.A friend of mine turned down some aluminium end covers to fit over the pump bodies using some longer scews countersunk and has cured the typical twin wetsumping.

Tolly · Post by **Tolly** » Thu Jul 16, 2009 10:19 pm

Hi Wilko, have you any pictures/photo's or drawings of said aluminium end covers. I have wetsumping problems but I won't mention how I manage it as it may become controversial.
What do you think of the auto adv/ret gear?