Hot Coil

[maverick]

For a long time now I have been worried about how hot the ignition coil gets on my car,like too hot to touch after a 15 min journey.
The coil was from LD parts and is the Lucas Sports coil described as 6 volts:see explanation on website
I dont think the coil is at fault.


This seems to be correct as my car is a MK1 and ballasted,before this I had a standard motorparts coil that also got very hot,the coil is mounted in the standard place,but raised up so as not to touch the block, I dont think that engine bay heat is the cause.

Question:does any one know what makes a coil get so hot ?and if It could be a faulty ballast,does anyone know the correct way to test if it is working correctly?

My car has Luminition fitted a runs ok,but I have a long run planned and am corncerned about the heat
I am sure it is wired correctly with white/slate wire to poitive side of coil and white/red to ballast an purple wire(luminition) and black wire to neg side of coil.
Thanks in advance Mark

[martin]

Hiya Mark, all conventional coils get hot, that's why the wiring lives in an oil bath, the current is considerable, 20.000 volts usually, and heat is the result. Some Stag owners have moved them to the bulkhead, but I doubt it makes much difference. It won't blow up on you, and I've never known one damage any other component, so carry a spare and carry on ! Martin.

[V Mad]

Coil should not be to hot to touch unless you leave the ignition on with engine stopped for a long time (not a good idea).
To check if ballast is wired correctly in series with coil do this test:
1. Connect coil NEG to chassis.
2. Switch on ignition
3. Measure volts at coil POS. This should be about 6 volts. If it is about 12 volts it is wired incorrectly.

[maverick]

Hiya Mark, all conventional coils get hot, that's why the wiring lives in an oil bath, the current is considerable, 20.000 volts usually, and heat is the result. Some Stag owners have moved them to the bulkhead, but I doubt it makes much difference. It won't blow up on you, and I've never known one damage any other component, so carry a spare and carry on ! Martin.

Hi Martin ,
Thanks Spare allready in boot an ready !

Cheers mARK

[maverick]

Coil should not be to hot to touch unless you leave the ignition on with engine stopped for a long time (not a good idea).
To check if ballast is wired correctly in series with coil do this test:
1. Connect coil NEG to chassis.
2. Switch on ignition
3. Measure volts at coil POS. This should be about 6 volts. If it is about 12 volts it is wired incorrectly.

hI Chris,thanks for help,followed your suggestion and get reading of 9.7 v,at POS side of coil ,pressume this test is with ignition on but engine not running?

Mark

[ChasR]

Depends on the coil. The oil filled Ballast coil I got from a Southern Stag specialist was hot to the touch. The Bosch red sports coil on the car (I think they use wax instead of oil) is surprisingly cool.

Oddly enough, my old MGB on its original Lucas coil was also hot to the touch but the ignition never really gave me any issues.

[maverick]

Coil should not be to hot to touch unless you leave the ignition on with engine stopped for a long time (not a good idea).
To check if ballast is wired correctly in series with coil do this test:
1. Connect coil NEG to chassis.
2. Switch on ignition
3. Measure volts at coil POS. This should be about 6 volts. If it is about 12 volts it is wired incorrectly.

Hi Chris,
Followed your suggestion,and I get a reading of 9.7 volts at coil POS side,

Thanks Mark

[maverick]

hi Chris,
Voltage reads 9.7 volts at coil positive,please can you advise me,
Thanks Mark

[maverick]

hi Chris,
Voltage reads 9.7 volts at coil positive,please can you advise me,
Thanks Mark

Sorry about duplication,really need to bounce this back up for V.Mad Chris

Thanks

[maverick]

Update on Hotcoil.
I think I may have solved my own problem.
After reading lots of posts and studying wiring diagram,I think the wiring to my coil and ballast Resistor has been incorrect.

I had slate and grey wire to POS side of coil and orange/ white wires to both sides of Ballast.

Although it has always been this way in 11 yrs of ownwership,I have now swapped wires to single wire orange/white to POS side of coil ans slate/white to bottom of ballast with twin orange/white to top of ballast.

I now have a much cooler coil reading 6.5 volts on Pos side of coil instead of 9.7 volts.

I would still like someone to confirm to me that this wiring( single wire orange/white to POS side of coil ans slate/white to bottom of ballast with twin orange/white to top of ballast),is the correct format for my MK1 mod.On a side note there seems to be a spello on the Don Kennedy wiring diagram in that the wire colour marked form coil to ballast is shown as orange/white but described as WS ,WHITE AND SLATE,can anyone confirm or deny this is a spello or correct


The car runs fine but I was hoping for improved starting if the ballast had not been wired properly,but this was not the case this morning.

Any comment help on this would be welcome,
Thanks Mark