1945 bo mag timing

~If you move either the mag or the flywheel after removal you can still put it back by placing the flywheel slot back parallel with the ground [or line the flywheel LH Impulse marks up] & installing the mag so the matching lines line up. You will have 50/50 chance of getting it in correctly & if it won't start there, just remove the mag & turn the flywheel 1/2 turn re-install the mag & it should be back where it was.

~If you want to re-set the timing, or install the mag from scratch, just give us the mag make & model & we will give you the entire mag installation & timing procedure. The initial mag set-up varies a little by mag type, & manufacturer..... .....

If you are replacing it, so long as you have it turned so its male drive coupler fits in the female drive slot in the end of the governor shaft, it can be made to work, but may or may not (50/50 chance) be 180 out of time, in which case you could simply reverse the top and botom plug wires and she would still run. Then, of course, once shes mounted in but not full tightened down, you rotate it CCW to advance timing or CW to retard.

The long answer is if you want it as original where the top plug wire terminal fires the left cylinder and the bottom the right (to eliminate the 50/50 chance).

When the left cylinder is at TDC on its compression power stroke (you can remove the plug and see when shes suckin in {piston coming down on intake} or blowin out under pressure {coming up on compression}, at TDC on its power compression stroke, thats where the Left Hand Impulse mark on the flywheel is at the 3 O Clock position lined up with the mark on side of tractor. At that point, the mag should just be snapping over to fire the left cylinder, and that female drive cog slot in the governor shaft end should be flat horiziontal. The mag at that point should be rotated to have its rotors first leading brush tip just before (top and left of) and ready to snap pass the caps top plug terminal. To insert the mag in the governor then, I rotate the flywheel backwards (before ready to snap over and fire) just enough to where the slots match up and you can insert teh mag. If set this way, the top plug will fire at TDC on power compression stroke and the bottom at the right cylinders TDC. Like I said above, the worse you can do is get it 180 out, in which case you have to reverse the top and bottom plug wires.

Even if the flywheel is covered and you dont need to fool with its marks, with the left plug removed, you can tell when that piston is coming up under compression (blowing pressure out the plug hole) and that governor female mag drive cog slot is coming just before flat horizontal, and rotate the mag to get it in the slot with its rotors first leading brush tip just before (top and left of) the caps top plug terminal, you will be right.

Good Luck, post back any more questions. Ol Jogh T Nordhoff in Indiana.