Overheating ignition coil

I have a '70 series 2a, petrol 2.25,

problem is, when the engine has run for about half an hour their is a loss of power and it cuts out completly, the other day i was listening to the radio, parked up the engine not running but the ignition switch on, the coil blew itself apart with a puff of smoke, serious overheated coil!.

im going to fit a new coil, but will this just happen again?, is there a problem elsewhere???

all help appreciated!

It used to be the case that some coils used to have a ballast resistor, to reduce the load. It is possible that your old coil needed, but didnt have one or else there is being too much current being pulled thru it - unlikely. Check the voltage at the input side of the coil, just in case it is being over-volted.

its in the region of 12v, i think your right too, it aint the propper coil, says for use with ballast resistor (my bad)!

i have put an old coil off a mini on, lucas (12v ignition), but this still get pretty hot, i.e. it would burn you when you touch it! i think it may be buggerd as the car used to misfire?

dont want to leave it on for too long, afraid i would end up with a fecken oily black mess again!

think i should buy a new coil, what should i be buying?

thanks fer your help mate!.

Make sure you get a genuine 12volt coil that actually says 12volt on it. Lucas supplied me with supposedly the right one but not marked (think it said "DVB" or summat on it).Overheated and also Melted rotor arms in no time. Turned out the B stands for Ballast and I think without a ballast resistor they are about a 6 volt coil - hence the probs.

thanks, ill check inside the dizzy too, but i dont think there will be owt wrong as the engine wasnt running. cheers.