Poor Ignition Coil Reliability (thoughts?)

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Bill_qaz
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Re: Poor Ignition Coil Reliability (thoughts?)

Post by Bill_qaz »

svenedin wrote: Tue Aug 11, 2026 5:33 pm
Bill_qaz wrote: Tue Aug 11, 2026 4:26 pm Not even going to take it off, just going to reroute the black wire the other side of the HT lead and make sure the terminal is secure. The coating on the top looks like underseal :tu1:
Will know better when heater duct is moved to give better access. The duct isn't bolted to the inner wing as it was retro fitted.
On the cars that had the duct fitted at the factory, it is held on the inner wing with brackets. These are still available but generally poor quality and prone to rapid rusting. There's a Mini supplier (Nippy Cars) that sells nice black powder coated brackets that don't rust. My car has those brackets.

Stephen
Yes I bought a pair but with all the stuff on inner wing I'd have to move bits so just used 1 cable tied to bonnet pull to stop the pipe flopping.
20250213_151437 (1).jpg
20250213_151437 (1).jpg (764.1 KiB) Viewed 223 times
Regards Bill
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svenedin
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Re: Poor Ignition Coil Reliability (thoughts?)

Post by svenedin »

Bill_qaz wrote: Tue Aug 11, 2026 6:45 pm
svenedin wrote: Tue Aug 11, 2026 5:33 pm
Bill_qaz wrote: Tue Aug 11, 2026 4:26 pm Not even going to take it off, just going to reroute the black wire the other side of the HT lead and make sure the terminal is secure. The coating on the top looks like underseal :tu1:
Will know better when heater duct is moved to give better access. The duct isn't bolted to the inner wing as it was retro fitted.
On the cars that had the duct fitted at the factory, it is held on the inner wing with brackets. These are still available but generally poor quality and prone to rapid rusting. There's a Mini supplier (Nippy Cars) that sells nice black powder coated brackets that don't rust. My car has those brackets.

Stephen
Yes I bought a pair but with all the stuff on inner wing I'd have to move bits so just used 1 cable tied to bonnet pull to stop the pipe flopping.
20250213_151437 (1).jpg
As you say, with all of the stuff on the wing the duct could not sit against it like it does on those cars that had it fitted at the factory.

Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.

Stephen
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svenedin
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Re: Poor Ignition Coil Reliability (thoughts?)

Post by svenedin »

Looking at the workshop manual AKD530 the coil specified for the 1098cc is Lucas LA12 with a primary resistance of between 3.2 and 3.4 Ohms.

All of the internally ballasted coils on sale these days seem to be 3 Ohm with the exception of the Bosch Blue 922081083 which is quoted as 3.4 Ohms. Whether this small difference in resistance has any bearing at all on failure rates I don't know but it seems unlikely. At 12 volts an increase in resistance of 0.4 Ohms decreases the current flowing through the coil from 4.0 amps to 3.53 amps as compared to a 3.0 Ohm coil.

The voltage required to jump a 0.025" spark plug gap is around 8,000 volts at the pressure in the cylinder and with the presence of fuel. The voltage required is a lot less in room air. "Sports" or high output coils claim very high output voltages e.g 40,000 volts but at the standard plug gap they reach nothing like that voltage. These high output coils have very many more secondary windings (because they are similar to a step-up transformer) and so I wonder whether they are a lot more fragile as a result. Only reliable failure data (which we do not have) would answer this.

Stephen
1969 1098cc Convertible “Xavier” which I have owned since 1989.

Stephen
michael4
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Re: Poor Ignition Coil Reliability (thoughts?)

Post by michael4 »

Not long ago I removed the 'Spitfire Multispark' from the coil to distributor lead.

Guess what...no discernible difference.

I am inclined to open it up and see what is in inside.
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svenedin
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Re: Poor Ignition Coil Reliability (thoughts?)

Post by svenedin »

michael4 wrote: Wed Aug 12, 2026 9:53 am Not long ago I removed the 'Spitfire Multispark' from the coil to distributor lead.

Guess what...no discernible difference.

I am inclined to open it up and see what is in inside.
According to this https://www.nortonownersclub.org/forum/ ... spark-unit it consists of two ferrite washers and a gap. Sounds like Snake Oil like so many ignition related products!

Stephenn
1969 1098cc Convertible “Xavier” which I have owned since 1989.

Stephen
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