Need help with electronic ignition swap

Suzuki hatchback tech questions and answers.
weejimmy
Posts: 17
Joined: Tue Feb 19, 2013 5:07 pm

ok in the end i used the old coil with the resistor
ill see if i can get the su12 to work latter.
what is the advantage to the su12?
or will my old coil burn out eventualy ?
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Brayden
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Joined: Sun Apr 11, 2004 3:09 am
Location: Canberra ACT
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Electronic ignition is designed to run at 12V. With a coil and resistor it runs at 9V. So long as you run the old coil with the resistor you won't burn anything out.
F8B EFI turbo - Three pots and a snail.
ssc87
Posts: 97
Joined: Wed Aug 12, 2009 11:34 pm
Location: Newy

I was thinking about this and maybe is a big maybe, due to different coil design it is having an effect on the ignition timing and dwell angle. From my initial install i had timing way out and with small adjustments it made a huge difference, but never checked it at the same time as coil swapping.
If you can back to back testing with a timing light will identify if my theory is correct. :NFI:

I also would have thought the coil would only be running on 6v supply when using a dropping resistor as it is the same resistance as the coil winding and should have an equal voltage drop. Will need to chuck a multi meter on my mates stock hatch and see.
weejimmy
Posts: 17
Joined: Tue Feb 19, 2013 5:07 pm

ok i was off this for a while but today i had a quick look at it again,
i have now got the electronic ignition running great with the old coil and resistor set up,
i did however find i had a fuel leak. The screws holding down the top bit of the carburator were lose so the fuel was coming out of the join.
its possible that was causing the issues so ill take her a proper run and see if its still all good, then ill try swaping back to the new coil without resistor and see what the outcome is.
i have a timing light so ill be able to do it on the nose.
Eddie
Posts: 15
Joined: Sat Apr 04, 2015 11:27 pm
Location: Canberra

just found this information and it may clear up the issue you were having


Ignition Coils


Ballast and Non-Ballast Ignition Systems

Contact breaker (points) type ignition systems, as fitted to most Ford models up to around 1980 (although it lasted up to 1987 for the Capri), can have either a ballast fitted in the wiring loom or not.


What is a ballast?

Quite simply, it is a resistor that has the purpose of reducing the voltage to the coil.


Why do some ignition systems have a ballast fitted where others do not?

Originally, all ignition systems did not have a ballast fitted which meant that the ignition system used a 12v coil with a 12v feed from the battery via the ignition switch. Such a system works fine when an engine is running, but problems can occur when starting the engine. The starter motor draws a huge current from the battery leaving less energy to create a spark across the spark plugs. The result is a weaker than normal spark which is not ideal for starting an engine. This problem is worsened by colder temperatures and/or a worn starter motor which will draw even more energy for starting and leave even less energy for sparking. To overcome such a problem, ignition systems were changed to run a lower voltage coil (usually 9v), and these coils could still give the same output as the original 12v coils. In order to run such a coil, the 12v ignition feed runs through a ballast, reducing it to 9v at the coil. To assist starting, a 12v feed (usually from the starter) bypasses the 9v ignition feed, giving the 9v coil a 12v feed. The result is a better than normal spark which is ideal for starting, particularly on cold damp mornings. As soon as the engine has started, the 12v feed is cut and the coil will run on the 9v ignition feed.


How do I know which ignition system is fitted?

Ballast ignition systems were introduced in around 1970. Virtually all Ford models from this date should have a ballast fitted. To find out for sure, use a multimeter to check the voltage on the positive wire of the coil with the ignition on. Around 9v means you have a ballast, around 12v means you don’t.


Which coil should I use with a ballast ignition system?

Without modifying your ignition system, you can use any standard ballast coil or we offer performance ballast coils from Bosch (red coil 0221119030) or Intermotor (gold coil DLB110). Using a non-ballasted coil would mean that you are running a 12v coil on a 9v feed, resulting in a weak spark. You can however use such coils provided you remove the ballast resister.


Which coil should I use with a non-ballast ignition system?

Use any standard non-ballast coil, or we offer performance non-ballast coils from Bosch (blue coil 0221119027) or Intermotor (gold coil DLB105). Do not use a ballast coil. Although you may gain a performance advantage using such coils, failure will be imminent!
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