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MG MGA - Coil orientation

I've posted this on the B forum too.
There's a semi-heated debate in progress on another MG site, regarding coils, i.e., up, down, sideways.
Those who think down, for terminal insulation reasons. Those who are "uppers" for possible leak prevention and maximum oil coverage of the iron core, for cooling reasons. Then there's the on their side brigade, terminals horizontal, presumably best of both worlds.
What is totally absent from this debate is an input from Lucas, Bosch etc., who actually manufacture the things.
Has anyone had such a definitive input, or are we all working on habit and "old wives tales", as some would have it?
I'm trying at present to obtain an answer, no success as yet.

Allan Reeling

Alan. I too look forward with interest to you getting a definitive, manufacturers recommendation to your question on mounting oil filled ignition coils. Slightly off topic but I think relevant hopefully - after several failed coils, from the usual names like Lucas (Sports Coil), etc., all probably made in the same Chinese factory and inadequately filled with oil, I finally decided to pay a little bit more (not a lot actually) and do better. Bought from one of the big names (pertronix or magnecor or Lumenition or someone like, but cant remember which now) a solid coil, epoxy filled, which can be mounted in any orientation, doesnt get hot and has been bullet proof for some years now. Good luck with your oil filled coils but there is so much rubbish out there nowadays that I would recommend the alternative.
Bruce.
B Mayo

If its mounted sideways or down, the electricity will fall out; if mounted upwards, too much electricity remains. Best not to mount one at all!

But seriously, oil filled coils are sealed units with no air in them; it doesn't matter which way they are mounted. If they leak, its a bad seal, simple as that. Just look at the myriad ways coils used to be mounted by the auto manufacturers for visual proof that they came in all orientations. Seems like an argument for arguments sake alone.

Nick Kopernik

I don't know the definitive recommendation on coil orientation but my choice is to fit them facing upwards with the terminals facing upwards.

This is because I have had an expensive coil fail after it developed a leak and lost all its oil.
It was a Pertronix Flamethrower coil which was fitted with all the terminals facing downwards and I never noticed the leak until it had failed.

The replacement Lucas Sports Coil was then fitted facing upwards and although it also developed a leak from the high tension terminal, it continued to work.
I actually replaced it about 6 months after I spotted the problem.

Fitting the coil with all the terminals facing upwards also allows you to get to the connections far easier too than if they were facing downwards.

Cheers
Colyn
Colyn Firth

The coil doesn't care which way it's mounted. The only problem you may run into is if an oil-filled coil is mounted upside-down and leaks. Once the oil is gone it will likely overheat and fail. Then again they aren't supposed to leak.

Just today I removed a pre-war unsealed oil-filled coil from a car and mounted a more modern sealed type. The old one was mounted leads up because it's designed to be. I mounted the new one leads down because the HT lead fit better that way. Neither the car nor the coil seemed to care and neither did I. ;)
Steve Simmons

My coil has been laying lengthwise for at least 20 years. This allows the electricity to flow out better than standing straight up, where it has to be fuller to overflow.

Seriously, the original coil or at least a very old coil that came with the car, developed an oil leak due the bracket wearing a small hole in the metal cover 20 years ago. The replacement coil, laying down, as original, has 20 years on it. This doesn't seem like a major issue to me. Two coils in 60 years doesn't seem excessive.
Bill Haglan

Older coils used to have a burp hole on the rolled edge at the joint and were mounted horizontal with the little slit at the top so that if the coil overheated and burped it was usually only a bit of damp air that came out
Mounted like this the terminals were at 3-9 o'clock positions and internally covered in oil
It's my understanding that having the internal connections of the coil covered in oil is most important as that is where most heat failures occur
So based on that the coil needs to be mounted horizontal as above or if like most if not all newer coils without a vent,like this or nose down to keep the connector end covered in fluid
willy
William Revit

Willy,
That's always been my understanding. So until a manufacturer gets back to me (not holding my breath!!) and says NO< NO< BAD!!!! I'll carry on with that belief. Al
Allan Reeling

Allan
Just to add to this, I had an RS2000 Escort for a while and it drove quite normally but after driving it around for a while it would cut out on sharp RH turns like round a roundabout-checked all the wiring connections I could think of and it drove me mad until one night at the local,talking with the usual petrol heads and one guy said He'd had that and it was because the coil was mounted posts up and it had burnt the connection inside the coil--Because mine was ok until it got hot I thought I'd give it a flip over with the posts down and it stopped it doing it--bought a new coil anyway but I still think that was the cause of the failure
willy
William Revit

Willy,
Paul Hunt on the B forum posted this, which I think bears out your point.
The Leyland Workshop Manual describes a coil test-rig and includes the following:
"The coil must be mounted at an angle of 45 degrees on the test rig with the CB terminal uppermost and the coil case earthed.
"The mounting angle ensures that the primary winding take-off to the LT terminal is not covered with fluid and any internal tracking between the iron core and the primary lead will be shown up during the test.

"Earthing the case detects whether or not short-circuits to earth are present."
Allan Reeling

This thread was discussed between 27/08/2018 and 31/08/2018

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This thread is from the archive. The Live MG MGA BBS is active now.