No start '50 SA...Mag???

Farmall Super A, AV, 100, 130, & 140 1939 - 1973

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Sun Dec 01, 2019 6:58 pm

Half way through the first glass now! :D

I now have a some troubleshooting steps offered by Eugene (THANKS!) and will tackle them tomorrow.

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Rick Spivey
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Re: No start '50 SA...Mag???

Postby Rick Spivey » Mon Dec 02, 2019 7:25 am

Dale Finch wrote:Alright...I removed the H4 mag (eng at #1 TDC) , and checked the kill switch with a multimeter. It appears to be fine.

I'm curious, though...thinking I might have a short to ground somewhere, I checked continuity between where the wire from the start ("kill"?) switch attaches on the right side of the mag and the mag housing, and read a dead short. Seems like that's wrong, since, if I understand how it works, pushing the switch IN on the instrument panel puts that wire/terminal to ground. Could someone clarify what that wire on the outside of the mag does and how?


Dale,

The "primary" circuit inside the magneto has a termination point that is grounded to the chassis (a tab on the coil that touches the bar), and the other end goes through the points and to the stud where the kill switch connects. If you touch that stud to the mag body, and the points are closed, you will read a closed circuit (dead short). But when the mag is operating, nothing is making that final connection, or else you will get no spark (unless "kill" switch is activated). When the magnetic field is rotated, you create a flow of electricity in the primary circuitry, and a corresponding field in the secondary circuit (larger windings in the coil, which terminate at the nub that feeds the coil wire). When the points open, that field collapses in the primary circuit, and in the secondary circuit, resulting in the spark. The primary circuit collapses by way of the spark at the points, the condenser absorbs some of the energy to prevent "burning" of the points.

Hope that helps.
Rick Spivey
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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Mon Dec 02, 2019 8:24 am

Perfect, thanks! A PT session later this morning (bum hip), then back to the workbench. Probably can't do much until I get some new parts, but I can at least check out a few things. Will report back.

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Re: No start '50 SA...Mag???

Postby jeb2 » Mon Dec 02, 2019 10:39 am

Eugene has you pointed in the right direction. Since you have spark at the coil portion of the magneto but not at the distribution part of the magneto I would focus on the rotor and cap. Make sure the rotor timing is correct. Behind the rotor is a distributor spindle that must be timed to the rotor gear pinion. Remove the 2 screws and cover to access the timing gears. The smaller pinion gear will have one tooth that has small notch ground off on the end. that notched tooth must be lined up with the R on the larger distributor gear for correct rotor timing. The R mark is for clockwise rotating magnetos, the L is for CCW rotating magnetos. Also I would check rotor and distributor cap contact points before trying a new one.
For good H-4 magneto info check out the GSS-5035 Blue Ribbon Service Manual Magnetos here at Farmall Cub.com pdf manuals. Pages 51 and 52 explain the rotor timing gears.
John

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Mon Dec 02, 2019 10:57 am

Just ordered a Tuneup Kit which includes points, condenser, rotor, cap, plugs and copper core pre-made wires. I had a question for the seller regarding the condenser, and he responded quickly and in an efficient manner that impressed me. He also pointed out that the kit I was asking about was for an H rather than the SA, and the wire lengths were a bit different, with all else being the same. So I ordered the correct one and will let you know how it goes. :D

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Re: No start '50 SA...Mag???

Postby Super A » Mon Dec 02, 2019 1:45 pm

Dale Finch wrote:Just ordered a Tuneup Kit which includes points, condenser, rotor, cap, plugs and copper core pre-made wires. I had a question for the seller regarding the condenser, and he responded quickly and in an efficient manner that impressed me. He also pointed out that the kit I was asking about was for an H rather than the SA, and the wire lengths were a bit different, with all else being the same. So I ordered the correct one and will let you know how it goes. :D


Where'd you order your kit from?

Al
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"It ain't a !@*% A. It's a SUPER A!"

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Mon Dec 02, 2019 6:19 pm

Found it on eBay, sold by southernoak11
I tried to put a link to the exact item, but it automatically goes to my order info, with address, etc...but if you Google H4 Mag tuneup kit , then add the specific tractor model (for farmall super A). He sells kits for about everything. You can get the wires pre-made or universal (cheaper), and with or without various parts, like cap, rotor, coil, etc.

Main reasons I went ahead with no info on seller was his 100% rating, the prompt response to my question about the correct condenser length, his correction of my order to the proper kit for the SA, and finally, supposedly everything is made in USA. We'll see...supposed to arrive by/before the 10th.

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Re: No start '50 SA...Mag???

Postby indy61 » Mon Dec 02, 2019 6:23 pm


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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Mon Dec 02, 2019 6:30 pm

Yeah, when I click on that link, it defaults to MY personal order...wierd!
I assume you only get the regular eBay ad without my name and address??! :lol:

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Wed Dec 04, 2019 2:45 pm

The H4 mag tuneup kit arrived today (4th) via 2nd day USPS, after having been ordered on the 2nd...over a week earlier than promised!! So far I am impressed with the service, and when I opened the package, each item looks very good. The distributor cap has brass contacts inside and out...old one has aluminum inside with brass in the plug wire holes. Wires look good, and hopefully are the correct length.

Since I THOUGHT I had a few more days before its arrival, I have not cleaned out the old grease from around the inner gears. I originally was going to skip this step, since I knew it had been running 2 years ago, and just wanted to get this thing running so it could be sold. But I have spent enough money now, that it's silly not to finish it up right.

So, as soon as I finish my lunch, I'll head out to the garage and complete this product. I'll get back, also, if there are any problems.
20191204_141653-1328x747.jpg

20191204_141920-1328x747.jpg

20191204_142049-1328x747.jpg

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Wed Dec 04, 2019 4:00 pm

When I cleaned off the grease in the gear chamber, I saw the pinion gear appeared to be one tooth off from below the R mark (assuming the"chipped" tooth is the correct one...it's the only tooth that is different):
20191204_154828-1182x665.jpg

Not knowing how this SA ran when parked, should I put it back in the same position, or move it directly under the R?

I will go ahead and clean while I await your answers! Thanks.

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Re: No start '50 SA...Mag???

Postby Eugene » Wed Dec 04, 2019 5:29 pm

I have an excuse. CRS.

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Wed Dec 04, 2019 6:04 pm

Since I knew that is what the manual called for, I went ahead and put the distributor gear one tooth over so the pinion "chipped tooth" was lined up with the R.
20191204_175747-2124x1195.jpg

Will start reassembly with nice new parts, and see how it works!

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Dale Finch
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Re: No start '50 SA...Mag???

Postby Dale Finch » Wed Dec 04, 2019 7:25 pm

Got it all put back together, and tested it with just the coil wire to ground...a nice big white spark! :{_}:

But a few minutes ago, with my glass of wine in hand, I realized that out of habit, I set the points to .020 instead of .013!!! Arrrgghh!! So tomorrow I need to open it up AGAIN, and reset the points. Oh well, I should be pretty good at this once I'm done! In the next few days I'll get back over to the tractor and try to start it...thinking positive thoughts! :D

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Re: No start '50 SA...Mag???

Postby Lt.Mike » Wed Dec 04, 2019 7:57 pm

Dale you’ve got me thinking I should send you my Mag to rebuild! :mrgreen:
Quote by Gary Pickeral I like
"If it can cast a shadow, it can be restored"

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:hattip:


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