Chrysler V8 overheating ignition coil

scoop · Post by **scoop** » Wed May 28, 2014 7:23 pm

I have been asked to look at a friends Bristol 411 which I believe runs a chrysler V8 with electronic ignition, he broke down last saturday and the AA Man told him the coil was knackered as it was way too hot.
Since then he has swapped the coil with another one (not sure how old or what condition but don't believe it came from another Chrysler),
car started and ran for 30 mins before coil burst open spilling its oil.

My first thought is a faulty switching module.

any ideas on what could have caused this? or upgrades which may be suitable

Thanks

Keith

ChrisJC · Post by **ChrisJC** » Wed May 28, 2014 7:52 pm

If it were the other way around, i.e. points + coil for electronic ignition, I would say it's the coil.

However, electronic ignition shouldn't toast a points coil as far as I know.

Chris.

scoop · Post by **scoop** » Sat May 31, 2014 5:58 pm

Played with the Bristol Today, wiring diagram shows 2 ballast resistors 1 at 0.5 Ohms AND 1 AT 5 Ohms, checked both.
the 0.5 ohm had been shorted out with a piec of thick wire and showed 0.1 ohms the 5 Ohm reads 2.4 ohms.
Found a spare 5 ohm and replaced that one , removed the shorting wire on the other and it read 1.2 ohms so connected it without the short
Started the car and ran it for 20 mins and evrything was fine, nice cool coil. switched of but left the ignition on while I checked a few other things and the 0.5 ohm (1.5 Ohm which was shorted out) ballast started to crackle and overheat, so I guess I need a new 0.5 Ohm Ballast.
Alternatively I would like to mod the entire system using the Rover V8 Ignition mod as a guide, anybody know if it is suitable for a chrysler V8?

Denis247 · Post by **Denis247** » Sat May 31, 2014 11:04 pm

ChrisJC wrote:If it were the other way around, i.e. points + coil for electronic ignition, I would say it's the coil.

However, electronic ignition shouldn't toast a points coil as far as I know.

Chris.

Not all electronic ignition systems are capacitive-discharge. Some, including what I run, are just transistor-assisted ignition. Where instead of a large coil-current being switched by the points, leading to wear and burning, the current is a much smaller transistor switching current of just a few milliamps, with a transistor carrying the full current.

The coil still gets the full current hence would get hot like a normal points system.

DaveEFI · Post by **DaveEFI** » Sun Jun 01, 2014 8:51 am

If the coil is getting very hot in operation, it would suggest the dwell is wrong. The dwell is the time the coil gets to 'charge' before it is fired. Anything longer than needed gets wasted as heat. Assuming it is seeing the correct charging voltage.

Denis247 · Post by **Denis247** » Sun Jun 01, 2014 12:41 pm

Might just even be a case of moving the coil to a cooler location, in the airflow, or putting a heatsink on it. Much too much dwell would also show up in performance loss. Coill might alwo have dried out and lost it's coolant quite apart from the obviou of too much current .caused by wrong or faulty ballast.