Another Magneto Question

Fawteen · Jun 3, 2013

Got the condenser in my F4, thanks much for the clear instructions.

Still having issues however. I noticed when I took the mag apart to replace the condenser that the horseshoe magnet didn't seem very strong. It was magnetic, but I could set it on a steel plate and pick it off very easily.

So, two questions:

How strong should the magnet on a magneto be, and how does one go about remagnetizing it?

gene bender · Jun 3, 2013

Don't worry about it.

Fawteen · Jun 3, 2013

???

Could you expand on that a little?

Nebraska Cowman · Jun 3, 2013

I'm with Gene. Magnets can be recharged pretty easily. Most anybody who messes with hit and miss engines could probably steer you in the right direction. But I do not believe that the magnet strength is all that critical. If it will pick up the plate it should make a spark.

Fawteen · Jun 3, 2013

Ah. Dang. This thing is driving me nuts.

Started out as a moisture problem. Had been raining for days, tried to start the tractor and got nothing.

Used a heat gun on the points and inside the cap, got it to start but it ran REALLY rough, 3 cylinders at best and one of them not all the time. Lotta backfiring through the muffler. Seemed to run a little better if I retarded the mag to just short of cutoff. Next morning it wouldn't start at all.

Took the mag off, cleaned and regapped the points, put new wires and plugs in, no change.

Took the mag back off, swapped the condenser, double checked that it was timed correctly (#1 on TDC, verified by checking the valve lash).

Took the carb off, cleaned it (a little crud in the bottom of the bowl, passages all clear, no sign of water, no big issues) verified that it was getting fuel, left the air cleaner connection off for now.

Also checked compression, 90 PSI +/- on all cylinders.

Watched the rocker arms while cranking (electric start) and no sign of stuck valve(s).

Prior to this problem it has been running like a top and starting right up. If I wasn't already bald, I would be from scratching my head.

Zachary Hoyt · Jun 3, 2013

Could the cap be cracked or have a carbon track or something? If you had a spare one handy that might be a good thing to try changing.
Zach

Tom Fleming · Jun 3, 2013

well guys, on the magnet strength question, the impact of a weak magnet is a weak spark at low RPM's. I have a magnet charger, but not sure where you are located. I am in western PA and would be happy to charge it for you. for an F4 magnet, it should be able to hold its own weight when placed sideways on a piece of steel or similar. If it won't hold its own weight, it could use a charge.

To make a point, I had the original mag on my F12. would NOT start with the crank, but would fire up and run if pull started. Recharged the magnet, and she starts up fine with the crank. More magnetism, hotter spark at low RPMs.

as far as what symptoms you are experiencing, on the F4, make sure the distributor disk is clean. Make sure all carbon brushes are moving and not "sticky". Make sure there is continuity through the transfer post from the 2ndary on the coil to the cap. Lastly, make sure the safety gap is not closed up. If I remember correctly, the safety gap should be around 7/32 + not -. I'll get the manual out and double check.

A clean and correctly set F4 mag, with a fully charged magnet will throw a "knock you on your butt" spark with just the impulse......don't ask me how I know...........

teddy52food · Jun 3, 2013

The stronger the magnet, the hotter the spark. The energy of the spark has to come from the magnet. Remove the magnet & the magneto is dead.

teddy52food · Jun 3, 2013

Get that new condenser checked as it may be weak and leaky. I have a tester & I send them back if they don't check out perfect.

Nebraska Kirk · Jun 3, 2013

A clean and correctly set F4 mag, with a fully charged magnet will throw a "knock you on your butt" spark with just the impulse......don't ask me how I know...........

I like your analogy, Tom :lol: BTDT!! :lol:

gene bender · Jun 4, 2013

The H-4 mags I have on the A and Bs I fasten them in the vice turn them over with batt drill then with each wire hooked to a sparkplug on a metal bench I can check the fire at impulse and different speed and I have never worried about how strong the magnet is. I have taken them apart and cleaned the armature and magnet to be sure its clean and not covered with rust. After test I know it will work on the tractor and I will use a heat gun on the coil to see if it works when heat from engine gets running.

Tom Fleming · Jun 4, 2013

Gene, you are right for an H4 mag, as it has an Alnico magnet which is an alloy of iron, aluminium, nickel, and cobalt. It has a high coercivity (resistance to loss of magnetism), so they rarely require the magnet to be recharged. The E4A and F4 (both use the same magnet), which is a hard iron magnet, DOES need to be recharged on occasion. IHC actually had a standard magnet charger as a dealer tool because of that.

IHC F4 Magnet Charger:

Tom Fleming · Jun 4, 2013

BTW, if you will be at Red Power, let me know and I will bring my magnet charger with me. If anyone needs/wants their E4A or F4 magnet charged, pls send me a note or post here. Besure to bring a "keeper" with your magnet because once the mag is charged, if you don't put a keeper on it while not on the magneto, the charge will drain off quickly. A keeper is just a flat piece of steel long enough to span both legs of the horse shoe magnet.

John M · Jun 4, 2013

MR Fawteen sir! If youll shoot me an email, Ill tell ya how you can recharge that magnet at home. In fact, the instruction are somehwere in the archives here, but the pics are long gone. Ive done several with success using that method.

SweetFeet · Jun 4, 2013

Fawteen,

If you have any old mechanics or machinists in your area, they may have a charger.<p>Husband got some E4A magnets (same as F4) charged. Before charging, I could just remove the keeper bars with ease. Now you have to fight to get them off of there... pull/slide sideways at the same time. I can no longer just pick one straight up off of a magnet.<p>The old guy who charged it, checked it prior to charging and he could lift the keeper off easily. After he charged it (which took about 1 1/2 seconds and made a spark & poof)... he could not "lift" it off his charging unit - he had to "slide" it off the front using both hands because it was that strong magnetically.

Tom Fleming · Jun 4, 2013

I was wrong about the safety gap. It should be 5/16" or 10/32". 7/32" is a whisker shy.

Fawteen · Jun 4, 2013

Thanks for all the input. I'll let you know how things progress.

Question: Is the "safety gap" the distance between the button on the top of the coil and the stiff wire that goes to the primary contact behind the distributor cover?

Fawteen · Jun 4, 2013

Doh. Never mind, I finally found a picture that points it out.

Fawteen · Jun 4, 2013

Took the mag back off.

Opened up the point gap a touch.

Cleaned the distributor disk and carbon contacts.

Checked the continuity between the secondary contact and the coil, cleaned and snugged up the coil contact a bit.

Because I've had the carb off and the fuel pump apart, I rigged up a gravity feed tank to be sure I was getting fuel.

Cranked up and ran, a little ragged but it ran. After it had been running a bit, I cracked the petcock on the fuel line to be sure the pump had primed.

I'll finish putting it back together and tweek the carb a little and I think I'm there.

Thanks for all the help!

Fawteen · Jun 4, 2013

BTW, after reassessing the strength of the magnet, I didn't bother attempting to re-magnetize it.

Earl-IL · Jun 4, 2013

Make sure your cond. wire doesn't short out on the alum. cover.

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