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Calling H magneto Experts

Hey Red!

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BTD

09-13-2001 11:11:24

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I need to tap some wisdom in timing the magneto on an H. Here is the procedure I am following, gleened from past posts, the Antique Tractor Bible, and ATIS. I am now thinking of seeing if a "Magneto's for Dummies" book exists.

1. bring cylinder one (closest to radiator) to TDC (using thumb over plug hole to verify compression stroke) lining the first of the pair of marks on the main pulley with the indicator pin. The main pulley has three marks, a lone mark is separated from the first pair and doesn't seem to correspond with anything.
2. Rotate the magneto so that it has just clicked and the rotor brush is directly under the pin for cylinder one, to simulate the mag just firing for cylinder one at TDC. Hopefully the driven lugs on the magneto match the drive on the tractor, I have had to monkey with the rotor drive gear to get this, I think I'm going to regret that action.
3. Install magneto with the body of the magneto as close to the engine block as possible.
4. The instructions I have say to rotate the engine one complete revolution to TDC of the next cylinder in the firing order, for my H that would be cylinder three. (One set of instructions I have says this is indicated by bringing the main pulley once around to the first of the pair of marks again.) Unfortunately, the magneto clicks before I get that far around. So when I get to that postion, I rotate the magneto away from the block hoping for the click that tells me I have the magneto timed. I have never got the click. Not even close. When I got this mag to run the engine before I must have just lucked out.

I must be doing something wrong. My instructions manuals for my M differ enough not to be very helpful. How should I be interpreting those marks on the main pulley? I had to take the magneto off to give it a tune up and swap some parts. Now the thing gives great blue sparks and sends a jolt up to my shoulder if I hold it wrong! -Thanks for the help! BTD

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Farmer Bob

09-13-2001 22:09:45

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Re: Calling H magneto Experts - Hey Red! in reply to BTD, 09-13-2001 11:11:24

BTD, (Check your email) I'm no expert but...you probably have an H-4 Mag on that H and it is a clockwise mag. Ensure you have the "R" on the distributor spindle lined up with the chamfered tooth on the rotor gear pinion gear. (If it was a Counter-clockwise mag you would line up the "L" on the spindle with the chamfered tooth on the rotor gear pinion). If you have an older version of the H-4 you may not have the round bakelight with the "R" & "L" on the spindle. In this case there will be two teeth on the distributor spindle that have their ends partially cut off at an angle. If this is your type of spindle, set the two marked teeth staddle of the one marked tooth on the rotor gear pinion.

The H-4 mag with clockwise rotation was used on the A, B, U-2, H, W-4, I-4, O-4, U-4, IU-4, M, W-6, I-6, O-6, U-6, IU-6, and T-6. These mags had serial #'s H4-xxx,xxx and had a spark range of 35 degrees.//FB

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F-Dean

09-13-2001 17:13:23

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Re: Calling H magneto Experts - Hey Red! in reply to BTD, 09-13-2001 11:11:24

Take to valve cover off and watch the valves to make sure you are at TDC of the compression stroke.

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Michael Soldan

09-13-2001 15:16:20

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Re: Calling H magneto Experts - Hey Red! in reply to BTD, 09-13-2001 11:11:24

BTD, you don't need to be real close. some where around TDC and the first mark should work, once running you can pivot the mag on the mounting bolt to get it right on. My expert friend told me to have the mag ready to click on # 1 and as you put it on it may appear to be out of whack but get it in place and the first movement of the engine will fire it at TDC. I had to do this with the M and it fired immediately. My expert friend also says there isn't much to go wrong in a mag, mostly it just needs to be cleaned. The only thing you could go wrong on is being out 180degrees. Check your wiring and it should fire. good luck from Mike in Exeter Ontario

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jmyt_47

09-13-2001 12:34:34

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Re: Calling H magneto Experts - Hey Red! in reply to BTD, 09-13-2001 11:11:24

Sounds like you almost go it. The first notch on the crankshaft pulley is TDC. The next pair of notches that are closer together are 22 and 30 degrees advance markings.

I can't help on the rest.

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BTD

09-13-2001 16:06:42

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Re: Re: Calling H magneto Experts - Hey Red! in reply to jmyt_47, 09-13-2001 12:34:34

So the two markings about an inch apart are NOT the TDC mark and ? The one all by itself is the TDC mark? -BTD

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