Re: Timing Farmall B

Posted by lee on August 04, 2004 at 12:39:32 from (24.24.95.246):

In Reply to: Timing Farmall B posted by BEL@IN on August 04, 2004 at 06:13:59:

I have always set them up so the impule coupling trips at TDC. If this cannot be accomplished within the slots at the mounting flange then you probably need to re-mesh the magneto drive gear a tooth this way or that way to get the impulse coupling firing at TDC. I'll try to explain but a good manual will likely do better than I. First you set TDC. You can do this many ways but I do it by aligning the flywheel mark DC/1-4 with the mark on the clutch housing front cover as
viewed thru the hand hole in the clutch housing underneath the tractor. Remove the #1 plug and rotate the engine til #1 plug is coming up on compression. From under the tractor continue rotating til the marks above are in register. TDC is set. This is quite accurate as the flywheel diameter is quite large. From the description, your mag is retarded too far. The impuse coupling you say has not fired and you cannot make it fire with the slots. Given that, remove the magneto.
Remove the magneto cap. Turn the drive coupling clockwise til the rotor aligns with the number 1 plug position on the cap. This can be a little tricky but do your best to get the rotor centered on the #1 cap position. Install the mag without turning the drive coupling. If the drive coupling will not engage the drive lugs on the drive shaft you need to re-mesh the drive shaft so it lines up. Pull the drive shaft out just enough to rremesh it and then push it back in. Play with it til you get the couplings aligned with the rotor pointing at #1. Now you can proceed to time the mag. Retard the mag by turning the top of the mag towards the engine (cw as viewed from the drive end of the mag) to the extreme of the slots and tighten it down. Turn the motor once again til #1 is coming up on compression. Get under the tractor and bring the timing marks into register as above. Loosen the mag bolts slightly and slowly rotate the top of the mag away from the engine block (CCW as viewed from the drive end of the mag) til the impulse coupling just fires.
That is the mechanical timing set point. Tighten the mag. If this does not work for you, try the procedure again. It seems complicated but is quite simple. Now you know why lots of guys just adjust til it seems to run good. Running too far retarded the tractor will be down on power. You can also put a timing light on it and check and adjust while running but that's a story for another day. Oh, by the way, the impulse coupling only works at low speed. It cuts out after starting. And the tractor timing is fixed in the mag. I'm not sure off hand what the timing setting is in degrees but it's fixed, there is no mechanical advance mechanism..

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