Info on FBO ecu unit
heat is caused by current flow in the coil.
they are deisgned to deal with it.
so in a situation where the coil and module that runs it, are matched some what
or so time was taken to set points gap (basically dwell)
you won't be far off when running, and the coil should not get excessivly hot.
It may be too hot to touch but it won't be oozing oil and bulgeing i.e over heated
if you were to run an 8 volt coil at 12 volt you might have a problem the coil won't last long
current casues heat, so on an HEI set up, i like to make sure that my coil energy is biased a bit towards higher voltage. i want to run it as standard as possible
high voltage tends to go hand in hand with shorter and lower current flow and a slightly shorter spark.
hence i make my spark plug gaps 40 45 thou which fits with the spec. higher voltage spark with a reduced current flow.
smaller gap produces a spark at a lower voltage and consequntly a higher current flows for a longer period and that heats up the coil and can burn out the centre contact in the cap.
Dave