TOPIC: Electrical problem

Looking for some ideas I have a problem with my coil getting extreemly hot which results in the engine cutting out after about 20 minutes. The car then won’t start until the coil has cooled down after a couple of hours.
I have interchanged and renewed coil
Spark plugs and dwell angle checked.
Points not burnt.
Alternator shows it’s charging battery.
Wiring is correct on coil.
Help
Thanks
Mark

The symptoms point towards having the wrong sort of coil fitted. There are two types of coil 'Ballasted coils' and 'None ballasted coils' Fit the wrong one and it will get very hot and fail. The following link explains it nicely Coild types The X1/9 is the none ballasted type and has an external ballast resistor which is the bit of kit sitting below the corner of the windscreen (or it is on mine). As the article say it is easy to covert one to the other and to make it even more confusing to leave the original parts in place - my system is completely none standard but the ballast resistor is still in place, but not connected to anything. A failed ballast resistor usually means your car won't start

Thanks, this is very interesting, I’m thinking some one has messed about with it before I owned the car.
I’m now thinking the car has a ballast resister, probably has the wrong coil and only one wire on ignition side, I will do some investigation
Thanks
Mark

Is this the ballast resistor for ignition coil

No, that coiled wire below the windscreen is in the headlamp circuit; dim dip for daylight running lights I believe. There's no coil ballast resistors on x1/9s.

I agree you've probably got the wrong coil, it should be a 12V coil, try googling the markings on the coil to see what voltage your current one is.

Thanks, the coil is new 12v 3ohms which I have purchased from Eurosport. I have tried 2 other coils and the same happens with them

Judging from this blog by Powerspark it sounds like you have a standard coil.
(About halfway down the page)
blog.simonbbc.com/ballast-resistors-resistance-and-coils/

To confirm I have a non ballast coil, still problems and can’t get to the bottom of it, I have now renewed points and condenser but still the coil gets very hot on idle after 20 - 30 minutes then spark breaks down and engine dies. Won’t start until coil cools down.
Any more ideas would be helpful
Thanks

What ignition system do you have? Are you still running points/condenser (I am) or do you have some kind of electronic ignition?

No electronic ignition, just standard points and condenser

Curious....

My next thoughts would be either the points gap/dwell angle is miles out but you say that checks out OK. Are you able to check it with an oscilloscope?

My suspicion would then fall on the rev counter. Does it work, and read correctly? It is connected to the coil, so I'd disconnect it anyway and see if that makes a difference.

Thanks for the ideas Martin, today I have checked the dwell with a dwell meter and it’s spot on.
I also disconnected the Rev counter lead from the coil, unfortunately the same thing happened the coil got really hot and the engine died, although this time it seemed to run a bit longer ( 45 mins ) engine idling.
Would it be anything to do with amps going into coil from ignition or am I clutching at straws now
Cheers
Mark

Hmmm... Are you certain that it's the ignition that's causing the engine to cut out? If you douse the hot coil in cold water does it come back to life? Reason I ask is that one of my cars used to cut out after 20 mins or so and that was fuel vapourisation; the fuel pipes were routed along the cylinder head and not clipped to the bulkhead as they are supposed to be.

Other thoughts... how's your earth strap between the engine/gearbox and the body? How good are your plugs/leads/distributer cap/rotor arm? Is the cap/rotor arm the correct one with the right clearances? Which spark plugs have you got and are you running resistive leads? Do you have the radio suppressor on the coil still, that could be breaking down with heat?

Lots of questions... a bit of a brain dump!

I was going to mention the earth straps as well. Always worth checking their condition, especially the one down by the bottom of the gearbox.

Thanks for the latest thoughts, today I have changed the distributor cap and leads, same thing happened, then I removed earth strap from gearbox cleaned of and refixed, that didn’t work either.
So just to recap the coil gets really hot after 30 mins, if you had to hold it on your hand you would drop it. Then the spark gets week ( I have had it on a online tester ) engine dies and won’t start until coil cools down. This is a standard 1500 car with no modifications.
Ps free parts for anybody that can sort this out for me