Author Topic: 1934 Model Z magneto drive.  (Read 352 times)

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Offline Rispo

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1934 Model Z magneto drive.
« on: 23 Jan 2023 at 11:03 »
I am at present restoring a 1934 Douglas model Z 600. I am missing the magneto drive coupling piece. I would appreciate it if some one could send me a photo of what it looks like.
What I have made so far is very hard to get into correct alignment.
Regards John



Image converted to linked file to correct distorted display. Please see Taking photos with mobile/cell phone - Dave (Admin), 23Jan2023
« Last Edit: 23 Jan 2023 at 11:26 by Dave »

Offline Dave

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Re: 1934 Model Z magneto drive.
« Reply #1 on: 26 Jan 2023 at 02:13 »
Anyone able to help out here?

Offline eddie

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Re: 1934 Model Z magneto drive.
« Reply #2 on: 26 Jan 2023 at 09:13 »
I have never worked on a model Z engine but it is a development of the S/T6 engine, so I would expect most parts to be similar, if not the same.
   From your photo, the first thing that strikes me is that the spacers under the magneto look to be non standard. On the S6 they are headed pins with nothing protruding from the top (this makes it easier to align the magneto). Secondly, the drive from the stub shaft to the magneto is single sided on the S6 (having once got the timing correct, it is impossible to then time it up on the wrong cylinder). The drive dog that goes on the end of the magneto has just a single arm that locates in the slot in the stub shaft - the drive is taken on the solid side of the arm - the non-driving side is drilled for a ball and spring (which is trapped in the arm) - this prevents any backlash in the timing, and unnecessary rattles.
  If you have already assembled the engine without timing the magneto, you may need to remove the timing cover to re-mesh the gears to get the correct timing - this is simple - just slide out the idler between the mag and inlet cam, time the magneto and refit the idler. If you have to remove the timing cover, leave it loose until the engine is back in the frame with the primary chaincase fitted and the engine through studs fully tightened, then tighten the timing cover nuts. If the timing cover nuts are not left to last, you may end up with the valve gear not being correctly clamped in place, resulting in further engine damage.

  Hopefully, some of this will help,
                                                  Regards,
                                                                Eddie.

Offline Rispo

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Re: 1934 Model Z magneto drive.
« Reply #3 on: 27 Jan 2023 at 09:09 »
Thanks Dave and Eddie for your replies to my very first post.
I never new the magneto was mounted on stub shafts all I had was the imprints into the housing to go by. I have made a flat one piece mounting from 3mm aluminum for the magneto to sit on that shims can be added underneath. But the problem of miss alignment was still present when turning by hand. As yet i haven't assembled he engine or tried to time the magneto. I have discovered the taper on the magneto has .017thou wobble so this is going to be corrected before i attempt to check the alignment further. When i work out how to reduce photos i will post some more. Attached  is a photo of the drive dog i machined up to fit the slot in the drive.
Regards Rispo



Image converted to linked file to correct distorted display. Please see Taking photos with mobile/cell phone - Dave, 27Jan2023
« Last Edit: 27 Jan 2023 at 20:01 by Dave »

Offline Rispo

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1934 Model Z magneto drive.
« Reply #4 on: 27 Jan 2023 at 09:25 »
More photos

Offline eddie

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Re: 1934 Model Z magneto drive.
« Reply #5 on: 27 Jan 2023 at 11:39 »
Rispo,
          From your latest photo, I see your bike has a Lucas magdyno, whereas the S6 has a BTH magneto. However, this should not affect the way the unit is fitted. I have just taken the magneto off my S6, and got some photos of the drive (see attachments). The 4 headed pins that the mag sits on have a .750"dia head x .200" deep and a locating spigot .187"dia x .125" long. I guess the Z/Z1 models have the heavier duty drive because it is also driving the dynamo.
   Hope the photos are of some help,
                                                      Regards,
                                                                    Eddie.

 

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