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Magneto intermittent, rougher.

Posted: Sun Oct 20, 2019 11:17 pm
by ivaldes1
Hi all, I've had my T for about 3 years now, in all that time magneto has worked perfectly. Car ran better on magneto. I recently changed the transmission bands to Kevlar. The magneto has become unstable. Several times for band fuzz on the contact. Today no magneto again. As before, I checked it this time and there was only a little big of band fuzz put it together. I also took out the key switch panel. I bought a new key switch two years ago and it has been working fine until now. All of the screws on the back side of the switch were loose so I snugged them down. Magneto came back but now the car runs better on battery, when I switch to mag it runs rougher. What could be wrong?

-- IV

Re: Magneto intermittent, rougher.

Posted: Sun Oct 20, 2019 11:47 pm
by ivaldes1
'a little *bit of band fuzz so I put it *back together'

Re: Magneto intermittent, rougher.

Posted: Sun Oct 20, 2019 11:55 pm
by Steve Jelf
I suspect you have two different problems that happened to show up simultaneously. I wonder why there's band lining fuzz. Cracked or rough drum? For the magneto problem I would check voltage at the mag post and at the coil box. You may find that there's trouble between those points, inside the switch.

Re: Magneto intermittent, rougher.

Posted: Mon Oct 21, 2019 1:25 pm
by John kuehn
If you got the car to run again on mag gently move the key while it’s running on the mag position and see if engine runs better or more erratic. Then switch it on battery and do the same thing. Could be something is not making contact in the switch like it should.
Check the mag terminal closely and make sure the spring is making a good contact and is centered over the lead button that’s on the field coil.
When I installed a new mag ring in my 19 Roadster I found that the lead button wasent exactly centered when it was rebuilt. It’s OK now since I bent the spring on the mag terminal so it makes a good contact with no intermittent issues that were happening before I centered the spring on the contact.