How to test a magneto

[AllisG]

I have a 1936 AC WC all hand crank with a magneto, Is there a good way to test the magneto to make sure iam getting spark??

 

[El Toro]

Make sure the tractor is out of gear. If the mag is still on the tractor, disconnect the No1 sparkplug wire near the radiator and hold it away from the sparkplug about 1/4" and have a helper to hand crank the engine. Look for a hot blue spark jumping from the plug wire to the sparkplug as the engine is being cranked.

If there's no fire clean the points in the mag with some 320 wet or dry until they're shiny. Then see if there's any fire from the plug wire while the engine is being cranked. Make sure your switch that grounds out your mag to stop the engine is in the "Run postition" when you try this. If you have fire choke the engine and see if it the engine will start. Hal

 

[gene bender]

I would take ALL the plugs out so it cranks easy. Hook any wire to a grounded plug. Then when you turn the engine over you can watch for spark at the plug. If it fores on that one it should fire on all but it sure wouldnt hurt to check each one with its wire that way you know all wires and plugs work. Just bedause one has spark doesent mean they all do.

 

[Jim in Ma.]

1. Remove #1 plug wire
2. Grasp same wire end firmly with one hand
3. Turn the crank with the other hand

You "Will" Know if You Have Spark.

 

[James Howell]

Checked the magneto on "John B" our 43B yesterday for spark.

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<li>Make sure the tractor is out of gear and both brakes locked</li>

<li>Make sure the gas is turned OFF</li>

<li>Open both petcocks (compression release) if applicable</li>

<li>Remove both spark plug wires and then remove both the spark plugs</li>

<li>Get a shop rag to cover the open spark plug hole to keep from getting sprayed by any residue gas that might be in the cylinder</li>

<li>Connect spark plug #1 back to the spark plug #1 wire and lay it against the frame, block, manifold, etc.</li>

<li>Either turn off or dim the lights in the shop</li>

<li>Roll the flywheel over by hand or with the starter</li>

<li>Either you, wife, girlfriend, significant other, or friend can watch for a spark</li>

Repeat the process for spark plug #2.

On our WICO magneto, #1 was not firing, but #2 was firing.

Changed out the magneto with another rebuilt WICO and was good to go.

Hope this helps and be careful.

 

[JMS/.MN]

What the others said is fine, but if the mag is off the tractor, hold the mag in one hand with your hand over the plug wire holes, turn it over with the other hand. Depending on how much you twitch, how high you jump...depends on how good the mag is. Seriously, if it is dead or just tingles, it needs to be rebuilt.

 

[Billy Shafer]

You will know if you have spark. After you get off the floor.

 

[greygoat]

You guys have got it all wrong! You're sposed
to put the plug wire on your tongue!

 

[mkirsch]

Actually that's a good way to ensure the mag is NO GOOD...

If you're holding it, you will drop it and break it.

If it's on the tractor or on the bench, you will be so mad from getting bit that you'll beat it to pieces with a hammer.

 

[corvettebob]

Your supposed to have your wife hold the wire!!!

 

[Jim.ME]

Your supposed to have your wife hold the wire!!!

Welcome to the Forums.

A word of caution. You aren't going to win many friends here by reviving a 12-year-old thread for a Ha-ha. Due to a recent software change many members here are already trying to cope with old (technical) threads coming to the top, when they are used to old threads staying where they were posted in time. Most are very willing to help with your current tractor problems and give advice, so bring that stuff on, they will be all over it.

 

[560Dennis]

1. Remove #1 plug wire
2. Grasp same wire end firmly with one hand
3. Turn the crank with the other hand

You "Will" Know if You Have Spark.

Really?

 

[Tim PloughNman Daley]

I have a 1936 AC WC all hand crank with a magneto, Is there a good way to test the magneto to make sure iam getting spark??

Can't answer for a JD Magneto but here is some info on the MORSE-FAIRBAnKSFMJ-4B73 unit used on the FORD N-SERIES TRACTORS. MigHt want to try your I&T F0-XX Manuals for a JD magneto...

Tim Daley (MI)

 

[Jim.ME]

Can't answer for a JD Magneto but here is some info on the MORSE-FAIRBAnKSFMJ-4B73 unit used on the FORD N-SERIES TRACTORS. MigHt want to try your I&T F0-XX Manuals for a JD magneto...

Tim Daley (MI)

Tim, it is a 12-year-old post, he hasn't posted for almost 3 years, and he asked about a mag on an Allis Chalmers WC, not a JD mag.