IHC H4 Mag

ZiggyR

New member
I have another post on stationary engine forum on a y69 continental. Just got it and first chance I’ve had to mess with it. Trying to fire it up and not having much luck. It’s throwing a good spark 1/4 inch or better but think the timing is off. But thought I’d pull the mag and clean things up, check and gap the points, etc. then put it all back together and try to time it.

On the side of the mag is a little pot metal housing mounted with 2 screws. A bolt runs thru it laterally. Spring inside, double nutted on the other end. Obviously some kind of adjustment. The housing is broken. What is this thing and what does it do. And are replacements available? I’ve hunted a little but on other h4 mags I’m seeing, there’s just a little cover without any type of adjustment so I’m a little confused.
 

mmcdonald

Subscriber
A picture would be good but I'd guess you're describing the manual grounding apparatus. Most of the H4 mags we see just have a nut screwed on the condenser and a screw outside to connect a kill/grounding wire to. Some of the mags were equipped with a mechanism so you could ground it right there mechanically without an electrical wire to another location.
 

ZiggyR

New member
You are correct, it’s the kill switch. Once I took things apart, I could see that’s what it was for. I did some more digging and found a replacement on eBay for $100. I think I can find a cheaper way to shut it off (if I ever get it running).

Thank you for the quick reply. Much appreciated
 

cobbadog

Active member
Sounds like you may have a timing issue but not the magneto itself as it was sparking well. Checking the spark timing to the piston and also check your valve timing if these are good then you have a fuel problem providing you have good compression.
 

ZiggyR

New member
I was able to get the machine running. Set the timing by the marks on the flywheel. I could get it to hit a few times so figured I was close. I think the issue was compression. Don’t think it had run in 40+ years. Used quite a bit of penetrating oil in the cylinders so had to keep pulling the plugs and blowing compressed air to dry thing out. After a lot of starting fluid and cranking, she finally fired up. Runs really good but I have bb holes in the radiator. So just a couple short runs. I think once I can run it longer it will be a lot happier
 

cobbadog

Active member
Squirt some thick oil down the spark plug hole, not a lot just one maybe two squirts from an oil can and try to start. This will confirm your theory of stuck rings causing low compression.
If it does start and run, just run it above idle for a while and see if it improves the compression. If it does not improve it may be valves not seating or stuck or worn rings.
 
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