Practic'in what I preach... H-4 mag Remove Repair and Replac

Bob

Well-known Member
I answer a lot of posts on here about mags, and have worked on LOTS of them over the years, especially the H-4's.

I don't do it as often as I used to.

A customer had "dies when hot problems" with his "A", and I needed to put a coil in it.

<img src = "http://i167.photobucket.com/albums/u125/27Grainfield/061008_144800.jpg">

I yanked off the cap, rotor was pointing straight up. GOOD ENOUGH. Easy enough to put the mag back on that way.

I took the mag with me, and proceeded with replacing the coil. As usual, the coil was STUCK on it's laminated "armature". I should have just sawed it off, but tried to press it out, "delaminating" the core!

Fortunately, I had a "donor" mag handy, and grabbed it's coil core.

Got the coil all in place, installed new points, and CAREFULLY set them to .013", using a dial indicator, rather than taking a chance on touching them with a feeler gauge with possible oil residue.

I took a look in the little rotor drive gearbox. Someone had set the gears up with the rotor one tooth retarded,so I corrected that.

I went to the customer's place today, and re-installed the mag.

Someone had previously installed the cap upside-down, and it was "cocked" a little, not sitting down on the locating pin, so I turned it 180º and swapped the sparkplug wires accordingly.

I had made a match-mark on the mag flange and mounting flange, so the timing was back where it was. I then tried to find the timing mark on the flywheel, to no avail.

Just to verify it was CLOSE, I started the tractor, which INSTANTLY fired up, and ran pretty well.

Shut it down, and tried AGAIN to find the timing matk on the flywheel. NO USE.

I pulled the #1 sparkplug, and used a length of wire to follow the piston travel, and find TDC.

THEN, I took another look for the timing mark, and there it was, the most faint line you could ever see. I marked it with a red paintpen, then proceeded to check the timing. The mag was tripping quite a bit AFTER TDC, so I reset it to trip JUST after TDC (in case they ever crank-start it).

Boy, does that little engine PURR now!

It's been rainy here, I hope the weather holds, as they plan to mow with it in the morning. I HOPE the new coil fixed the "dies when hot" problem!
 
If you are referring to the tractor I was working on, there is a cast-in pointer just ahead of the bottom of the flywheel that you can line the mark on the flywheel up with accurately.

And, it WILL be in the center of the bottom inspection hole.

What tractor are you working with?
 

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