H spark trouble

[Ed Hotaling]

Just a recap, H with H4 magneto sputtered and quit. Spark from coil wirw to ground, but not from plug wires to ground. I replaced the cap, rotor, points & condensor with no change in the situation.

I tried disconnecting the kill switch wire on the off chance that there is a partial short that weakens the spark and still no change. Someone suggested that the gears behind the rotor could be out of time. I haven't taken them apart, so I thought that couldn't be the problem. I was just taking a closer look at it and found that the rotor has about 15 degrees of rotation in free play. That doesn't seem right to me.
1. Is that right?
2. If not, can I get just a set of those gears to change out?
3. If it is o.k., it was suggested that the coil may be getting weak but I should check the magnets before replacing it. How do I get at the magnets to check them?
This was a rebuilt mag about 15 years ago and has been quite reliable.
Thanks,
Ed

 

[Farmall Ed]

Ed, I have 2 H's one is 12 volt and has a regular distributor,the other one has a mag, I can put new points in the 12 volt one and not have any problems,but the mag one always gets out of time and I have to go thru the timing process to get it running again, you may have to time to get it running again, those little gears for the rotor are a PIA. Ed

 

[El Toro]

You can easily check to see if the mag is out of time by bringing No1 piston to TDC on the compression stroke then look to see where the rotor is pointing, Should be at the No1 plug tower on the cap. Even if its out of time you should see fire to the sparkplugs by holding a plug wire 1/4" away the plug and have someone to try and start the engine. Should have a hot spark. Hal

 

[teddy52food]

Unless the gears are worn out (stripped) or you are messing with it , those gears don't get out of time by themselves.

 

[Nebraska Cowman]

I am by no means an expert. The rotor will have some play. The magnet is a permanent alnico type. If you have spark at the coil lead then the problem is with with the cap, rotor or wires. The original cap had a carbon brush to pick up the spark from the rotor. If that brush is missing it may cause trouble. How hot is the spark from the coil? You need a good blue fire that will jump 1/4 inch gap. Orange fire won't cut it.

 

[teddy52food]

Do you still have spark from the coil wire? If yes then is is something with the cap and rotor. If no, then try the old condenser. Also, did you clean the points after you put them in. What are they gapped at?

 

[MIKE THOMPSON]

15 degrees of rotor turn is a lil excessive i was taught that there should be no more than 5 so i would take a look at the gears and see if they are worn/stripped and start from there

 

[Ed Hotaling]

The gears are good and tight, the play is where the driving gear slips over the shaft. I was wondering if a shim of some sort on the flat spot would help.

 

[Ed Hotaling]

The coil wire gives about a 1/4 inch spark to ground. I never heard about cleaning new points...they're set at 20 thousandths. As I recall that is where I have always set them.

 

[Ed Hotaling]

I honestly can't tell what color the spark is because the tractor sits in the sun and it's hard enough to see the spark at all. I do know it will jump about 1/4 inch or so. The cap and rotor are new from NAPA, but maybe I should check the center terminal with my ohmmeter...it wouldn't be the first time I got a new electrical part that was a stinker.

 

[Nebraska Kirk]

The points on the H4 magneto should be set at 13 thousandths. 20 thousandths is for the points in a distributer ignition.