Farm Equipment - WD45 with Magneto?

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WD45 with Magneto?

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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=138061
Printed Date: 28 Jul 2025 at 4:13pm
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Topic: WD45 with Magneto?

Posted By: Zsartell
Subject: WD45 with Magneto?
Date Posted: 03 May 2017 at 7:13pm

I have a 1951 WD tractor that has a WD45 engine in it. When I got it there was a hackjob done to change the magneto ignition to run on a coil instead. The tractor never really ran all that well and after sitting for a while I diagnosed poor compression on one cylinder and almost nothing on another. I rebuild the head and after replacing it I installed a full magneto setup off of a WD that a neighbor traded some work for. It has spark after cleaning it all up and I replaced the plugs and wires for good measure. I put the beveled gear at "C" and made sure it was a TDC. I cleaned out the carb although it could probably use a rebuild, it did run before with the carb in worse condition. For the life of me I could not get this thing to pop at all. I had fresh gas and even tried a little starting fluid. I double checked the timing a million times and nothing. For kicks I put the rotor gear between "C" and "A" and with some starting fluid got it to run (at least on the fluid). As of right now I'm just confused. Is there some strange timing differences from the magneto to the distributor it must have had when new?

Thanks,

Zach

Replies:

Posted By: WF owner
Date Posted: 03 May 2017 at 8:29pm

Are you 180 degrees off? To find true top dead center, you need to remove the spark plug and make sure you are on the mark on the compression stroke to time it correctly.

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Posted By: Zsartell
Date Posted: 03 May 2017 at 8:32pm

Yeah, I made sure I was at TDC by taking out the plug and feeling the piston with a wire come all the way to the top.

Posted By: WF owner
Date Posted: 03 May 2017 at 8:45pm

I hate to state the obvious, but don't forget you have a 4 stroke engine and it only fires on every second revolution (intake, compression, fire and exhaust). If you are timing it between the exhaust to intake stroke, the piston will be at TDC, but on the wrong stroke for spark. It has to fire between compression and power strokes.

If you remove the small cover under the flywheel, the flywheel should have a TDC mark to get it exact TDC.

Posted By: dawntreader74
Date Posted: 03 May 2017 at 8:54pm

there also is a timming mark on the flywheel for TDC' then check piston? when turn should fire on number 1

Posted By: Dakota Dave
Date Posted: 03 May 2017 at 9:51pm

are you sure the magneto is good when you turned it by hand before you installed it it should snap and produce a good spark. did you hook the battery ingition wire up to the kill stud on the mag. just disconnect it completly. # 1 must be on Fire on compression stroke. Snap the impulse coupling and back it up to the #1 position before installing it

Go Here http://dueyschutter.freeservers.com/photo6.html

Posted By: DougS
Date Posted: 03 May 2017 at 10:03pm

Remember that TDC will show at the top of the compression as well as the exhaust strokes. Be sure you are at TDC of the compression stroke. Put the C/A mag setting back where it was. When you know you are at TDC of the #1 compression stroke look at the mag rotor and make sure it is pointed at the wire that goes to the #1 cylinder.

Posted By: Zsartell
Date Posted: 04 May 2017 at 9:01am

Yeah, I appreciate the help everyone, but I did time it while at the end of the compression stroke and the magneto is giving me a good spark when snaping it by hand. There is only one mark on my flywheel and that is an "F".

Posted By: Larry in NC
Date Posted: 04 May 2017 at 9:13am

It sounds like you have checked out the obvious. Here are a couple of things you might want to try. Remove a spark plug. With the spark plug wire attached ground the end of the plug against the engine and have someone turn over the engine (hold the plug with pliers so you don't get shocked). See if you have a good spark at the end of the plug. This will tell you if you have spark all the way to the cylinders. (If you have not done so, it is best install new spark plugs. Old plugs may not fire as hot). I had a C magneto that had a frayed ground wire so it was grounding itself out. If you have spark, do the starting fluid test again. If the tractor runs on starting fluid, the problem is in the fuel. It could be a clogged sediment bowl, fuel line or the carburetor.

Posted By: Gerald J.
Date Posted: 04 May 2017 at 9:37am

Yes that will show there is some spark to the cylinder but a spark at the plug at normal atmospheric pressure is no proof there is enough voltage to get a spark at 100 psi or higher cylinder pressure. The spark has to jump more like 3/8" to 1/2" in air to be sure to jump .030" at the plug in the cylinder.

Gerald J.

Posted By: Zsartell
Date Posted: 10 May 2017 at 9:03pm

OK, so I rebuilt the carb (sort of unrelated, but it needed it) and still nothing. Maybe a few pops here and there. When I went to rough time the magneto I tried putting it at TDC and rocking the mag back to get the impulse to snap and it will only snap after I turn the engine over a little by hand and its well into the power stroke (so the timing is extremely late). So from what I can see is that the timing from the governor gears on a WD45 is not compatible with a WD magneto. You just can't get it to snap at TDC like it should. It's not even close. So now I am going to go back and rebuild the rickety magneto that someone previously turned into a distributor and re-install that.

I've been told by everyone that putting a magneto from a WD on a WD45 engine is no big deal, but I just don't see it happening without pulling the governor and moving the gear to better line up with the magneto timing.

Posted By: WF owner
Date Posted: 11 May 2017 at 2:17pm

It might be simpler to change it back to a (original equipment) distributor. You can sometimes find them on ebay for a reasonable price.