No spark

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Drivemaine
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No spark

Postby Drivemaine » Mon Sep 02, 2019 8:34 pm

Hello everyone, new member here with a no spark issue. Long story short, recently pulled a 1957 Morris Minor Convertible out of a shed where it has sat for the past 10 years. The engine had been upgraded to a 1275 with a Petronix electric ignition by the previous owner. After cleaning the fuel system, all the oils, plugs wires etc... then I turned my attention to the ignition system. I found that there is no spark anywhere. I have tested the coil and it reads 12v at both terminals, resistance is approx 3.2 ohms (it is a lucas sport coil), however there is no spark from the coil king lead when grounded. I also took the leads within the distributor and with the ignition on I brushed them on the chassis to ground them and got a strong blue spark which I would imagine shows the distributor low tension leads are functioning (please correct me if I am incorrect). I have since replaced the coil and still no spark. I am exhausting my knowledge (I’m quite mechanically inclined, yet this is reserved for the “mechanical” part of vehicles not the electrical portion... any help would be appreciated

beero
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Re: No spark

Postby beero » Mon Sep 02, 2019 9:44 pm

Forgetting about the electronic ignition for a moment and concentrating on the coil.....
With the ignition on you should have 12v on one of the wires to the coil. Leave this one connected, disconnect the other, then use a temporary earthed lead and put it on the other terminal. When you REMOVE this earth, as if the points were opening, that is when you would expect a spark from the king lead. Let us know, this will prove the coil first and we can then move on from there.


Drivemaine
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Re: No spark

Postby Drivemaine » Tue Sep 03, 2019 10:19 am

So I’ve ditched the electronic ignition for now and put points and a condenser in. I also found that I still had a coil from a ‘69 Midget I owned a while back. I checked for spark with the king lead and there it was. It’s not incredibly strong but it’s there. I then checked for spark through the distributor and it is producing spark to the spark plugs. I think a new coil will probably help with the strength of the spark. The engine almost caught when I cranked it, the timing needs to be adjusted at least it has potential at this stage. I don’t always like to wake up after a long sleep either so there are some cobwebs that need to be sorted out after the long term storage this car has had. (Yes compression is good 150-160 across the four cylinders)

geoberni
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Re: No spark

Postby geoberni » Tue Sep 03, 2019 1:07 pm

If the car is a bit 'unknown' to you I'd check the Coil polarity connections too.

See this post of mine from earlier in the year; I had a weak spark issue, but didn't know it at the time. Car had been like it for who knows how many years/decades.
viewtopic.php?f=12&t=70183&hilit=spark
Basil the 1955 series II

Image

myoldjalopy
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Re: No spark

Postby myoldjalopy » Tue Sep 03, 2019 3:33 pm

OK so now - if I understand you correctly - you have tried three coils and swapped out the electronic dizzy for one with points and you seem to be getting a weak spark. What we don't know is what has caused 'no spark' to change to 'weak spark'.
You would have been wise to have tried 'beero's' coil test first and I would recommend you do that now - after checking polarity of the coil as suggested above.......if car is +ive earth then the +ive coil terminal (or may be marked 'CB') should go to the dizzy.......if -ive earth then vice-versa. Also check all electrical connections are clean and sound. And re-check points and plug gaps. Then, if you flick the temporary lead 'beero' mentions against the engine block, or other good earthing point a few times, the king lead should spark strong and blue if the coil is good.
Of course, it is possible the electronic ignition had failed and - assuming the coil tests good - your condensor is dodgy. If that is the case, get a new condensor from the Distributor Doctor which will be 'proper job'.

Drivemaine
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Re: No spark

Postby Drivemaine » Tue Sep 03, 2019 5:15 pm

Thank you all for the replies. The car is running very well now. I rechecked all the coils and wasn’t happy with the resistance readings on the newest one and was suspect on the other two as the spark was weak. Went out and purchased a new coil and after some coaxing and fiddling with the advance it started right up and is running very smooth. I need to do some timing adjustments now and sort the brakes.

Drivemaine
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Re: No spark

Postby Drivemaine » Tue Sep 03, 2019 5:16 pm

Oh and to add, yes I am now running the points and condenser set up. Took five minutes to pull the distributor out and get all the bits put in and adjusted.

myoldjalopy
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Re: No spark

Postby myoldjalopy » Tue Sep 03, 2019 6:43 pm

Well I am glad to hear the car has been coaxed back to life - very satisfying after it sitting idle for 10 years. 8)
I hope your new coil proves reliable but, as many on here have reported modern coil failures, it might be wise to look out for a good, old 'proper job' coil as a backup. There is a school of thought that the old ones are much more reliable. Similarly, as you have reverted to the points dizzy, there have been many reports of modern condensors giving up the ghost prematurely and I would get a backup one from the Distributor Doctor, whose quality made, reliable condensors are top-hole.


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