John Deere B Timing question

jd2cyl1943 · Jan 3, 2023

I bought a mag for my JD B and was going to retime the cam and gov to mount the mag to test for spark. It's pretty much stripped down to the frame, with the crank and cam shaft the only remaining engine parts installed. My plan was to retime the cam because its off, then to retime/reinstall the gov. I know I don't really need to retime, but this is my first restoration/overhaul so I thought some practice wouldn't hurt anything, right? Anyway I can't seem to make the cam timing match the service manual instructions. And I can't even make the governor go back into it's housing much less retime it. I admit that I'm very inexperienced. Any suggestions, anything at all? Thank You in advance

This post was edited by jd2cyl1943 on 01/03/2023 at 05:32 pm.

Mark Poss · Jan 3, 2023

You can test the magneto for spark by plugging a couple of wires into it with spark plugs on them and turning the lug on the back side of the magneto.
No need to mount it on the tractor.

Den N Ms · Jan 3, 2023

The spark plugs will have to be grounded to the magneto case to get any spark from them.Turn the impulse with a crescent wrench to test it.You can test the mag with it clamped in a vice with the mounting ear to hold it ,spark plugs can then be laid on the vice to ground them.

This post was edited by Den N Ms on 01/03/2023 at 06:49 pm.

Mike(NEOhio) · Jan 4, 2023

If the crankcase cover is off you should be able to find the timing marks on the crank and camshaft gears. There should be another set of marks on
the camshaft and governor gears. If all is correct the slots in the mag drive coupling should be horizontal when LH piston is at TDC. If not you'll
have to pull off the left bearing cover of the governor to see the marks. Careful putting it back on. Put some Vaseline on the balls to keep them in
place.

MSD · Jan 4, 2023

Has the camshaft been removed from the tractor? If so you need to align the timing marks which can be kinda hard to find. Just a small dot on the crank gear. If it
hasn't been removed chances are it is right yet. To put the gov. back in the gov. housing you need to turn the flapper so it is all the way up to the side of the gov.
housing. Turn the gov. so that the weights are pointed up and down and wiggle it till it goes in. You should be able to turn it after it is in to align the timing marks
on those 2 gears. Just pull it out some and lift up so you can turn it. When done right, the slot on the gov. mag end should be straight across when the crank is on tdc. Don't force the cover back on the housing. If it is binding chances are the bearing is not seated properly. push the cover in by hand a couple times as you tighten it and rock the crank back and forth to help seat it.

Gene Davis (Ga.) · Jan 4, 2023

Do not try installing the governor shaft/bearing left hand cover with the magneto in place, it will probably break the mag housing when you tighten the bolts. So put the governor bearing cover on first then mount the magneto after you tighten the cover bolts. Ask me how I know this?

Mike(NEOhio) · Jan 4, 2023

Test the mag as Den said, in a vice. Many have been tested hand-held and when it trips the holder is shocked and drops the mag breaking the cap or
case.

jd2cyl1943 · Jan 4, 2023

Thanks for all the advice. Gene, if you can't learn from your own mistakes, learn from someone else's

I think that the vice method is probably the best that I have heard. I definitely don't want to damage the mag., as the original one was stored in a shed which burnt down a long time I got the tractor.

John Deere B Timing question

jd2cyl1943

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Mark Poss

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Den N Ms

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Mike(NEOhio)

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MSD

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Gene Davis (Ga.)

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Mike(NEOhio)

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jd2cyl1943

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