Farmall Cub

I had an inquiry this week about how to time the rotor on a J4 magneto and since there is a spare magneto in one of my parts drawers, I took a couple pictures and emailed to the member making the inquiry. I thought maybe they would be beneficial to someone else also. To make it easier to see, I used some white paint on the mark on the rotor.

First picture is how the rotor and pinion gear should be timed. This is also how it should look just after the magneto trips at TDC on #1 cylinder. It is easier to get the gears right, if the magneto is off the tractor, then you can turn it backwards to get the marks lined up rather than fighting the impulse.


this second picture is as the gears look as the engine approaches TDC of #1 cylinder just before the impulse trips.


this is the position of the governor to magneto drive slot with the engine at TDC of any cylinder.

Thanks for posting the pics, Mr John. I took a mag down to DSCF to get it worked on. Mr Gary Dotson was kind enough to show me some things about a mag, and that was one of them. I put it in my 47 cub and she fired right up. Thanks, Mr Gary! And I'm sure these pics will help someone

No problem, Thomas, I enjoyed it! Good pics, John, should help a few folks.

thanks john, how about putting it in the how to section

Rob in NH wrote:thanks john, how about putting it in the how to section

It's there.

added another picture to the original post.

where can I get these photos

Here's a link to the "how to " forum. Not sure why the photos don't show up here. viewtopic.php?f=140&t=83108

Bob

The photos no longer show up on this thread because they were on the photo server Centurylink decided to shut down. Barnyard moved them to the Farmall Cub.com server though so they now show up in the HOW TO posts