06-06-2021, 12:02 PM | #1 |
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Magneto drive
Anyone have info on mag drives used on Model A, B, engines?
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06-06-2021, 01:28 PM | #2 |
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Re: Magneto drive
Gad, I haven't seen those in years. As I remember they mounted in place of the distributor.
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
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06-06-2021, 01:34 PM | #3 |
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Re: Magneto drive
Some were side drive. Drove off of the cam gear. Wico mags were popular for these.
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06-06-2021, 05:38 PM | #4 |
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Re: Magneto drive
I use a drive that Pete describes on my Bonneville engine. I removed the impulse but it starts easily with the starter. I don't like the top-drive mags because of the load they put on the small dist. drive gear.
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06-06-2021, 06:20 PM | #5 |
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Re: Magneto drive
Look at secretsofspeed.com
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06-06-2021, 09:04 PM | #6 |
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Re: Magneto drive
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Larry Shepard |
06-07-2021, 06:54 PM | #7 |
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Re: Magneto drive
Magnetos are mostly fixed timing since the whole body has to be rotated to change it at all and that could be very problematic for mounting. The housing has to be solid due to the torque it takes to pull the shaft through e-gap. The impulse coupling is only for a retarded spark during start phase. They are basically made for all out throttle usage. Kick back on starting with no impulse coupling may not be a problem with a lower compression engine but it could be for a high compression engine. I've replaced a few busted starters on aircraft engines when the spark retard wasn't working correctly.
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06-08-2021, 08:58 AM | #8 |
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Re: Magneto drive
The impulse starting mechanism also spins the magneto quick enough to get a spark when starting with a hand crank or starter. It winds up a spring and then lets the magneto loose when TDC is reached. When the engine is running a centrifugal device locks out the impulse mechanism.
I see all the magnetos mounted on the high performance engines at Secrets of Speed site mounted on the side and driven by the cam gear.
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
04-04-2022, 01:28 PM | #9 |
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Re: Magneto drive
I've got an "SM" Smiley Martin side drive with no mag base, and an unmachined Wells front timing cover and side timing cover.
If you see the attached photo, you can see both. |
04-05-2022, 11:32 AM | #10 |
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Re: Magneto drive
A mount for the mag can be fabricated and bolted to the B fuel pump bolts or the pan rail on A engines.
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06-21-2022, 08:41 AM | #11 |
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Re: Magneto drive
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06-21-2022, 12:00 PM | #12 |
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Re: Magneto drive
Sorry, I don't, and sold that setup years ago. I ground off a little of the sheet metal at the pan's edge to insure the mount always sat in the same way. Good luck!
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06-21-2022, 07:07 PM | #13 |
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Re: Magneto drive
Thanks for the reply, taken on board what you said regarding the top drive set up and looking at the side drive instead.
Thanks. |
06-21-2022, 08:11 PM | #14 | |
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Re: Magneto drive
Quote:
I start with a piece of 1/2" (13 mm) hex stock and turn it down to 5/16" (7.9mm) for the length of the thread on an original bolt and thread it. I then work out how much thread I want on the other end plus about another 8mm and cut the stock. I put the piece back in the lathe facing the other way and turn that end down to the same diameter and thread it. The result is a double ended bolt with the "head" in the middle. By removing one of the original pan bolts and replacing it with mine, I now have a place to attach my bracket. The bolt is put into the block using the "head" in the middle of the bolt and the bracket attached with a nut on the under side. I hope I have explained that clearly enough. Pictures are not easy to post.
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06-21-2022, 09:11 PM | #15 |
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Re: Magneto drive
Thanks but the question was more aimed at the fabricated Magneto mount that was mentioned, would like to see how it was done/how it was driven?
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06-23-2022, 03:11 PM | #16 |
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Re: Magneto drive
I can't' add any info for your question, but I do have a story about mags.
Back in the 70's and 80's I had an old '62 Harley with a mag, I would reach down and fine tune it while driving, and of course every once in awhile it would light me up like a Christmas tree, tell you what...you were wide awake after that...and sober too.
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Keith Shawnee OK '31 SW 160-B |
07-10-2022, 02:35 AM | #17 | |
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Re: Magneto drive
Quote:
Could you possibly post a couple of pics of the foot mount adapter from different angles? Would be very much appreciated. Chris. |
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08-18-2022, 08:06 AM | #18 |
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Re: Magneto drive
Running a Model XH Wico (foot mount) Magneto side mounted running off the cam gear,
the mag drive gear used appears to be a crank gear which would make the mag run at crank speed. Do they run a wasted spark system? It has been suggested they use a mag with a 2:1 reduction drive but I can’t find any info on a Wico X model with this. Can you run at crank speed, is it done this way? Thanks for any input, I have asked elsewhere also. |
08-18-2022, 12:04 PM | #19 |
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Re: Magneto drive
Most mags like yours do have a 2:1 reduction built in to the mag, so do not run a wasted spark system.
The gear is a crank gear, I hope it is steel and not a cast iron gear? I have broken an iron gear while running Bonneville, not good. |
08-21-2022, 05:45 AM | #20 |
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Re: Magneto drive
[QUOTE][IMG]http://IMG_4215.JPG
Tried to post pic but failed, I had a good look at the magneto and you are right about the reduction drive, the rotor button itself is geared and drives off the main shaft 2:1. And yes, I’ll be using a steel crank gear. The are obviously designed to run at crank speed and can handle the revs. Last edited by barrelnose; 08-21-2022 at 05:56 AM. Reason: Didn’t post |
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