Hot Coil

rfitzpatrick

Well-known member
It's 98 degrees, outside, I take my daily.

I can't keep my hand on the coil, it's that hot under the hood. I shoot it with my gun, it's 110 degrees F . Now I've no issues with performance, but isn't this quite hot?
Tks
 
They run cooler as long as the engine is running. If a person shuts the car off and leaves the switch on with the points closed, they can get pretty hot. An electromagnet can make some heat when it's energized. Always take care to insure you switch is in the off position before leaving the car for any length of time.
 
Kind of on topic but not, everyone should be aware that FS and Pertonics have a new better module, it is red in color instead of black. You have to run a different coil with it, your old coil will damage the new red module.
 
I have had my 31 stop running in rural Nevada about 90 miles from nearest town. Coil was hot so I turned it over waited for it to cool and drove home. I always carry a spare coil and distributor now.
Dan
 
I have had my 31 stop running in rural Nevada about 90 miles from nearest town. Coil was hot so I turned it over waited for it to cool and drove home. I always carry a spare coil and distributor now.
Dan

By the time I had the third coil fail on my car, I was ready to try something different. A very well experienced Model A man told me to turn the coil over (put the HT output at the top). I did that and in the 10 years or so since, I haven't burnt out a coil. The oil filled coils we get these days are a different kettle of fish from the ones used in the day.
I can't explain why that is so, just is.
 
The epoxy filled coils cool better in my opinion, the oil filled are not completely filled and upside down, oil settles and exposes the inside coil windings that are not getting cooled by the oil. My repro Ford script coil got so hot I couldn't touch it. Switched to a "Flame-thower" epoxy filled, 6 volt coil and now runs cool. I got it from Summit Racing Co.
 
The epoxy filled coils cool better in my opinion, the oil filled are not completely filled and upside down, oil settles and exposes the inside coil windings that are not getting cooled by the oil. My repro Ford script coil got so hot I couldn't touch it. Switched to a "Flame-thower" epoxy filled, 6 volt coil and now runs cool. I got it from Summit Racing Co.

You can tell an oil-filled coil just by shaking it. You can hear the oil sloshing around. Which obviously means it's not 100% full. When I put coils on my coil tester to heat up, oil-filled coils heat to 120° in about five minutes. The original Ford tar-filled coils take much longer, like fifteen minutes or more.
 
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