Hot Ignition Coil

[fmcdonald]

My coil is reading 7 ohms. It was so hot I couldn’t touch it. When I put the old coil back on, the 3000 BJ8 started right up. Is the coil bad? What would cause it to heat up like that?

 

[Bob_Spidell]

Short in the dielectric, probably. Is it a 'sports' coil?

 

[fmcdonald]

It’s a moss 543-020 standard coil.

 

[fmcdonald]

I get 3.6 ohms

 

[Bob_Spidell]

Offhand, I don't know if that's an issue; most coils have 1 or 2 ohms impedance, though some electronic ignitions--like Pertronix--spec a 3 Ohm coil (I think, don't quote me on that ). but I've run for years on (what I believe) are original coils in my BN2 and BJ8, both with Ignitors. Coils will heat up at idle, but shouldn't ever get 'pistol hot.' If a points gap is set up seriously too narrow the coil would heat up, but the car likely wouldn't run decently anyway.

Unfortunately, quality on aftermarket electronic parts has suffered for decades; last I checked, it's almost impossible to get quality points (for ignition and fuel pumps). Coils may not be an exception.

 

[Bob_Spidell]

First thing I check is the distributor rotor; even easier to swap out. I only carry 3 or 4 spares.

Edit: Oops ... this was meant to be in response to Reid's post below; brain backfire on my part, or?

 

[Editor_Reid]

Unfortunately, quality on aftermarket electronic parts has suffered for decades; last I checked, it's almost impossible to get quality points (for ignition and fuel pumps). Coils may not be an exception.

A local mechanic says the first things to check when your Healey stops running are the coil and condenser. Replacing them very often solves the problem, and they're easy fixes! The problem now is that, as you say, there are so many issues with recently made electronic parts that the fix may not last.