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MG MGB GT V8 Factory Originals Technical - Ignition coil for Rover 9.75 CR

Hi there,

I have a crack in the HT tower of my Lucas 32C 12 V electronic ignition coil and it causes occational missfiring. I would like to get a new coil, but canīt find a Lucas coil with the same number. The electronic ignition is from a 1984 Rover 3500cc Vitesse with 9.75 CR. The ignition modele is remotedly mounted with the coil bolted on to it.

Where can I find the proper Lucas coil, or what other coil can be fitted?

Thanks in advance

Erik
Erik

I would have expected a 1984 to have had a 6v coil and ballasted ignition, but of course anything could have been changed in the conversion. Any standard 12v or 6v coil will do, but you must make sure what type of ignition feed you have (i.e. ballasted or not) and fit the appropriate coil.

Disconnect the wires from the coil -ve and connect an earth/ground in their place. With the ignition on measure the voltage on the coil +ve. If you see 12v you have an unballasted feed and need a 12v coil, which should measure around 2.5 to 3 ohms on its primary. If you only see 6v to 9v you have a ballasted feed and must fit a 6v coil, which measures around 1.2 to 1.5 ohms on its primary.
Paul Hunt

Paul,
If I presumably measure the existing coil as being a 12V. Could I replace it with a Gold coil?

Erik
Erik

I'd still advise checking the ignition feed, you could have a ballasted feed but a 12v coil now instead of a 6v, which gives weak sparking. Just checking the coil and replacing like for like will repeat the error in that case.

FWIW the opposite situation i.e. a 6v coil on an unballasted feed causes overheating of the coil, possibly stressing of the trigger, certainly excessive burning in the case of points.

I have a gold coil which is a Lucas Sport 12v measuring about 2.5 ohms, something like that would be fine on an unballasted ignition feed.
Paul Hunt

Paul,
Thanks.
I know for certain that I have a 12 V feed, since I am not using the original white/green? ballasted cable. The coil present in the car is the Lucas 32C5 12V electronic which corresponds with the original specification of the twin-plenum/disc Rover SD1 Vitesse engine.

Is there any internal differences in coils distined for contact breaker ignition and the original sd1 distributer with the hall effect trigger and?

Regards

Erik
Erik

The 32C5 is a 6v coil (actually a 5v, which gives a higher spark output when used with 6v supply) and needs a ballasted ignition feed, that coil was used on late model MGBs with the 45DM4 ignition system. That is equivalent to the 35DLM8 electronic distributor which you may have. It was also used on 2.3 and 2.6 SD1s from 1977 with a ballasted ignition feed. You need to reinstate a ballasted feed, using it with full 12v will overheat it which could be a cause of the cracking you mentioned.
Paul Hunt

Paul,
Thanks. I think I have got it.

Erik
Erik

This thread was discussed between 12/08/2008 and 14/08/2008

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