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calling H4 magneto experts... another M with another issue


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ok, I have read the manual, I have watched 2 of Rachaels videos online, I have searched the web and found some solid gold wisdom from @pete23 but I am struggling with the H4 on the other M. got it out after a 2.5 year slumber, was running rough, a quick look found corroded terminals both inside and out of the distributor cap and on the end of the plug wires, so I ordered points, rotor, cap condenser, wires and plugs. when this tractor was put away it was smooth all the way through the RPM range and smooth at idle I took the mag out as It was necessary to do so to install the condenser, I did not orient the engine at that point and perhaps I should have. nothing was really nasty inside the mag that I saw. changed my pieces, adjusted the points and, following the service manual instructions went to reinstall the mag, in order to get the rotor to point at #1 I had to snap the impulse, ahead of actually snapping I couldn't get the mag coupler to align with the mag turned towards the block, I would have had to go somewhat closer to the block which of course I couldn't do. so I snapped the impulse and assembled. one more full crank revolution and adjusted the mag until it snapped. it wouldn't run at all, switched wires around a couple different ways on the plugs and no dice. finally by moving the mag around I got it sort of running. removal of the spark plugs showed that 2&3 weren't firing. the wires felt loose in the cap ( came from my IH dealer, both cap and wires) so I got the echlin cap and pulled the wires off my tractor and put them on, now I had it running but stuttering at idle. put a timing light on it and I am a solid 1.5-2" away from being move the mag away from the block gets closer, away gets farther away from the timing marks with a timing light, I took the little 2 screw cover off the rotor drive (which I had done before to check for proper lubricant) with the thought I had gotten things back together wrong, moved it one tooth to the left to advance timing, that seemed to make a small improvement. with the timing light I was now about 1" from the timing mark. still not a smooth idle, but better. 2 teeth made things very rough running. and one tooth advanced was a bad move. the actual distributor drive I did not have apart. it could be off but I don't know. 

what am I missing here, I have followed the manual, and followed the advice best I can of Pete23, and none of that is really conflicting with each other. I am thinking I will pull the whole thing apart tomorrow and start over again, but I am getting pretty frustrated. advice would be appreciated. 

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dont snap the mag. just get things lined up so the slot align with rotor in #1 position and away you go.in other words turn it backwards so your not fighting the impulse coupling. fine tune by moving the mag in the slots to fire at top dead centre. just did the same thing on a super wd9. fired right up after the paint job assembly.  all i do is crank it very slowly with the hand crank as as soon as it click make sure you stop that instant and check your timing marks. adjust as needed by moving mag and repeat., 

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What position should the drive coupler be at when #1 is at TDC? 
mine is roughly at 10 and4 

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What did you set the points to? I would suggest starting fresh with timing the mag to the engine. #1tdc compression, make sure that the mag gears are timed correctly. Changing them doesn't change when the mag will spark.. all they do is to align the rotor with the cap.  Turn the magneto backwards to align the rotor to #1 and install with top of mag toward the engine. Make one more revolution by hand to re-align timing pointer. Rotate mag away from engine until it clicks. Make another revolution and make sure the impulse trips right at TDC. Double check points to make sure that they are set at .013".

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8 minutes ago, Farmall Doctor said:

What did you set the points to? I would suggest starting fresh with timing the mag to the engine. #1tdc compression, make sure that the mag gears are timed correctly. Changing them doesn't change when the mag will spark.. all they do is to align the rotor with the cap.  Turn the magneto backwards to align the rotor to #1 and install with top of mag toward the engine. Make one more revolution by hand to re-align timing pointer. Rotate mag away from engine until it clicks. Make another revolution and make sure the impulse trips right at TDC. Double check points to make sure that they are set at .013".

Had them @ .015 when intook it apart the old points scarcely opened, not even sure how they worked at all. 

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The cam follower on the points will wear off quickly on a dist. cam that has set a while, it gets a lite abrasive rust.

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With the mag internally timed, points at .013 and installed as per instructions aligning with advise on here, the most recent of the videos by Rachel Ginsel, and an old post by @pete23 this is a close to the timing mark as i am able to get. Is it possible my drive is off a tooth? 

CAE5B1F4-4427-4659-A4C7-83299CC2E6AB.jpeg

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It looks like you are off a tooth...one tooth too early. The previous person to tune it up may have compensated for that with the extremely tight points like you mentioned. Less points gap gives later timing.  It's not difficult to remove the mag drive and re-set it. I had to go on service call to fix this same issue in a Super H this spring. A young fellow had taken the drive off to clean and paint in behind it... he almost got it back on right.

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17 minutes ago, Farmall Doctor said:

It looks like you are off a tooth...one tooth too early. The previous person to tune it up may have compensated for that with the extremely tight points like you mentioned. Less points gap gives later timing.  It's not difficult to remove the mag drive and re-set it. I had to go on service call to fix this same issue in a Super H this spring. A young fellow had taken the drive off to clean and paint in behind it... he almost got it back on right.

So i need to turn one tooth clockwise facing the impulse coupler?

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8 minutes ago, vtfireman85 said:

So i need to turn one tooth clockwise facing the impulse coupler?

yes if the gear turns clockwise , give it one tooth clockwise to retard it.  think or a car distributor when setting timing. turning it in same direction retards timing and turning it opposite of rotation advances timing. same on tractors.

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Ok, so first round the timing drive fell out after some wrestling with paint and stuck gaskets. Then i had no idea where i was so i timed the mag to #1 and made the drive coupler match, the. It took about 6 rounds of on and off to get where I think i want to be. I cant get this tractor to snap the impulse following the static timing process and I think the reason is in either this drive housing or it is the reason this drive housing looks like this. 2 of 4 holes are egged out (maybe with a torch?) and it only had 3 bolts in it. By turning 2 teeth clockwise from where the mag static times i was able to achieve the pointer lining up with the timing mark and it starts fairly well and runs pretty decently. What or why has this been done? 

B8F5BA76-4C87-4035-B441-F99A68B981FB.jpeg

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Why have the holes been egged out? The front cover and backing plate were changed to have a new bolt pattern to accomodate the hydraulic pump on the Super series engine. Your front end and mag drive are not from the same era. 

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16 minutes ago, R190 said:

 Thats an interesting tractor !

I see the shutter linkage do the shutters still work?

 

They do but somewhere along the way the radiator got smashed and now the shutters bind so i opened them and set the locknut. Needs a new radiator. 

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  • 2 weeks later...

There is a clockwise and counterclockwise marks inside on the gears on the H4.

Make sure you are on the right marks.

This is from memory and it has been years since I done this, so I may be backwards.

I put the mag on for #1 and turned the top of the mag towards the engine all the way and locked it down.

Then I used the crank to bring the engine up to the timing mark.

Then you loosen the mag and rotate the top away from the engine, very slowly, until the impulse snaps.

Lock down the mounting bolts as it is timed perfectly.

I crank mine most of the time and it has never kicked back and runs perfectly.

 

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If your impulse is not tripping as described by Diesel Dr and Farmall Dr above, it needs some attention. It is very important that the impulse trips,  especially if you are hand crank starting. The impulse does two things. It spins the mag fast to provide a hotter spark to allow for easier starting. It also retards the spark to TDC to ensure that the engine doesn't try to turn backwards and cause injuries to the person trying to start the tractor. I would try to lubricate the impulse with WD-40 or similar to free up the sticky mechanism. It may also have some significant wear causing it to  not function properly. 

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12 hours ago, Diesel Doctor said:

There is a clockwise and counterclockwise marks inside on the gears on the H4.

Make sure you are on the right marks.

This is from memory and it has been years since I done this, so I may be backwards.

I put the mag on for #1 and turned the top of the mag towards the engine all the way and locked it down.

Then I used the crank to bring the engine up to the timing mark.

Then you loosen the mag and rotate the top away from the engine, very slowly, until the impulse snaps.

Lock down the mounting bolts as it is timed perfectly.

I crank mine most of the time and it has never kicked back and runs perfectly.

 

 

3 hours ago, 12_Guy said:

If your impulse is not tripping as described by Diesel Dr and Farmall Dr above, it needs some attention. It is very important that the impulse trips,  especially if you are hand crank starting. The impulse does two things. It spins the mag fast to provide a hotter spark to allow for easier starting. It also retards the spark to TDC to ensure that the engine doesn't try to turn backwards and cause injuries to the person trying to start the tractor. I would try to lubricate the impulse with WD-40 or similar to free up the sticky mechanism. It may also have some significant wear causing it to  not function properly. 

I dismantled to check interior timing, cleaned and lubricated, i did not dismantle the impulse but i did check with a pick to make sure the impulse weights were free and springs were working, considering it runs like poo when timed to the impulse and better when the distributor drive moved 2 teeth forward I suspect at the very least the engine is not timed correctly, i want to have another exploration into the carb again, it was running out of power.. drastically, it came out neck and neck with a C with mounted belly blade. 

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Do not use a timing light on a magneto. As soon as the engine starts and runs fast enough to throw out the impulse lugs, the mag goes to 35 degrees advance. If you want to check your advance you can measure the diameter of the pulley and multiply by 3.1416. Then divide that number by 360 to find the distance for one degree. Times 35 to see how far ahead of the Top dead center mark the light should flash. 

If it impulses at the first of the double marks while hand cranking slowly it is timed correct and the gears are correct. 

One issue I have found on the H4 mags is, the wire that goes through the passage from the condenser to the points gets bad inside and will not carry current when it gets hot. One end has to be crimped after the wire is installed. The point end should have a "flag" wire terminal. .013 is correct for mag points.

When I take a mag off, I turn the engine until the rotor is pointing straight up. If it is wired correct with number one being at about 2 o'clock from the wire end, it should have just fired on number 2 and starting up on the compression stoke of number one. That makes it much easier to reinstall the mag and not fight the impulse spring. Once the coupling is engaged start the bolts and lean the top of the mag toward the engine and slowly bring the first of the double notches up to the pointer and stop. Tip the top of the mag away from the engine until it just trips. Tighten the bolts. Turn the engine one revolution, number four should fire at the mark. and watch to be sure it does not trip early. Adjust if necessary.   

Good Luck,

Hugh 

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You must make sure it doesn't trip before TDC. I have my magneto equipped H timed right at about the second (5 degree ) mark. I did that for hand cranking which I did often until I installed a alternator. You can rotate the mag in the opposite direction to line it up and you won't be working against the trip spring.

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