Coil Temperature

[Hamish Coutts]

Guys,

A quick question. Just got my engine running again after a major rebuild .

I was pottering about with the engine running checking for fluid leaks when I touched the coil. Yikes, it was hot. Like, far too hot to keep contact with. In all my years working on cars I've never come across this. Then again I din't think I've ever touched a coil after the engine had been running for 10 mins.

Pardon my ignorance but question - how hot should the coil get?

Coil is a Lucas white top. No balast resistor. Aluminuim casing is earthed.
I am using magnecor blue ignition leads with NGK plugs.
Rev counter is not acting unusually.
Distributor is fitted with Lumenition optical gubbins.

Am being neurotic?

Regards,

Hamish.

[type26owner]

Hamish,
That's caused from idling for long periods with an ignition system that does not have any intelligence. Because the dwell is fixed in angular duration there is a longer time the current is flowing through the primary circuit heating up the coil while it's sitting stationary. If you're going to idle like that it's best to provide a cooling source of air for the coil. BTW, the old style 25k volt coils run cooler then the useless high performance ones do.

The new micro-processor controlled hall effect switches vary the dwell based on the rpms and reduces that problem.

[john.p.clegg]

Have a look underneath the coil at the markings,you may have a 6v coil?
John

[Hamish Coutts]

Thanks guys, as informative as ever.
What you say makes a lot of sense, Keith. I don't plan to let it tickover for long periods. I was checking for coolant leaks and testing the otter switch to see if it worked properly in situ and fired up the fan.

It's amazing just how much a coil heats up in this kind of situation. I have made sure there is no chance of it coming into contact with any of the surrounding wiring.

Keith - I remember your eh, 'hostility' towards sports coils in previous posts and that is influencing me towards a new standard coil. What makes of coil do you rate?

Regards,

Hamish.

[type26owner]

I buy 'Standard' brand coils. They are probably only available here in the USA though. The truth is the high voltage coils give zero benefit put are a liablilty. If you goto the Innovate Motorsports website and read the technical article Klaus has written on this subject you'll get the straight facts of the matter.