998 Mini, standard engine . It was fitted with an electronic ignition set up but this stopped working so we replaced the original points etc. Now with the ignition on the wire from the coil to the ditributor quickly overheats. Why?
I'm sure it is all connected OK but if anyone has a clear diagram of how this should be wired I'd be grateful. If it is wired correctly what else could be causing the overheating, and could it be conected to why the electronic ignition packed up? We have tried changing the coil but the problem remained.
Thanks for any help
Steve

Distributor problems
Started by
Hughie
, Mar 03 2005 05:39 PM
7 replies to this topic
#1
Posted 03 March 2005 - 05:39 PM
#2
Posted 03 March 2005 - 06:13 PM
If I understand you, the electronic ignition stopped working so you replaced it with a points setup... correct?
There are several possibilities. Starting with the basics, the points are a switch going from coil (-) to chassis ground. The condenser is wired parallel to the points and its purpose is to eat voltage spikes that occur when the points open.
First, remove the dizzy cap and make sure you've set the point gap correctly. The heel on the moving arm of the points must be on a high spot (corner of a square cam lobe) when you set the gap. If the points don't open properly, the coil will always have current passing through it. The coil expects the points to interrupt the flow of current and if they don't, the coil and its low tension wiring will get hot.
Second (once you're sure the points are gapped correctly when on a cam lobe), remove the wire at coil (-) (the wire going to the dizzy... remove it from the coil, not the dizzy). Make sure the points are open and connect an ohm meter between the wire disconnected above and chassis ground. With the points open, the ohm meter should show an open circuit (infinite ohms). If you show low resistance, you either have a shorted condenser or a the points are not installed properly. To sort this out, first remove the condenser and repeat the resistance measurement. If you still show low resistance, look carefully at the points. Very early Lucas 23D/25D had points that used insulating washers for mounting. If these aren't on in the right place, the points behave like they're closed even when they're open. Likewise, it's easy to connect the spade lug on the condenser in such a way that it touches chassis ground inside the dizzy... shorting out the points. Obviously if you removed the condenser and the resistance went infinite, replace the condenser with a new one... or put it back in making certain that the spade lug isn't shorted to ground.
There are several possibilities. Starting with the basics, the points are a switch going from coil (-) to chassis ground. The condenser is wired parallel to the points and its purpose is to eat voltage spikes that occur when the points open.
First, remove the dizzy cap and make sure you've set the point gap correctly. The heel on the moving arm of the points must be on a high spot (corner of a square cam lobe) when you set the gap. If the points don't open properly, the coil will always have current passing through it. The coil expects the points to interrupt the flow of current and if they don't, the coil and its low tension wiring will get hot.
Second (once you're sure the points are gapped correctly when on a cam lobe), remove the wire at coil (-) (the wire going to the dizzy... remove it from the coil, not the dizzy). Make sure the points are open and connect an ohm meter between the wire disconnected above and chassis ground. With the points open, the ohm meter should show an open circuit (infinite ohms). If you show low resistance, you either have a shorted condenser or a the points are not installed properly. To sort this out, first remove the condenser and repeat the resistance measurement. If you still show low resistance, look carefully at the points. Very early Lucas 23D/25D had points that used insulating washers for mounting. If these aren't on in the right place, the points behave like they're closed even when they're open. Likewise, it's easy to connect the spade lug on the condenser in such a way that it touches chassis ground inside the dizzy... shorting out the points. Obviously if you removed the condenser and the resistance went infinite, replace the condenser with a new one... or put it back in making certain that the spade lug isn't shorted to ground.
#3
Posted 03 March 2005 - 06:30 PM
Have you connected a ballasted ignition coil to the direct 12 volt fed which was supplying the electronic ignition instead of to the ballast resistor?
#4
Posted 03 March 2005 - 11:22 PM
Thanks both.
Dan, can you explain a bit further. I get easily lost when dealing with electrics.
Thanks
Steve
Dan, can you explain a bit further. I get easily lost when dealing with electrics.
Thanks
Steve
#5
Posted 03 March 2005 - 11:32 PM
Which wire from the coil to the dissy? HT or LT.
If its LT check the points, especially the wiring
Siggy
If its LT check the points, especially the wiring
Siggy
#6
Posted 03 March 2005 - 11:58 PM
The ballasted ignition system was invented by Ford of Dagenham in the 1970's, it's a system to give easier cold starting. The problem it tries to solve is that when you dump the starter load on to the battery by turning the key, the available voltage at the battery drops dramatically (especially in cold conditions). It's to do with internal resistances of the battery and motor ballancing each other. The output of the battery can drop to as low as 6 volts which results in a weak spark from a 12 volt coil. So Ford invented a system where the coil is designed to run at 6 volts so that when this occurs the ignition system is still producing high energy sparks. The problem then is that the coil will melt when provided with 12 volts, so it is run with a resistor (or more often a resistive supply cable) in line which reduces the effective voltage to the coil to the required 6 volts. When the starter solenoid is active is bypasses the resistor, connects the coil direct to the (reduced output) battery and everything is hunkey dorey.
Rover started to employ the system in their cars in the late 70's and most Mini's from the early 80's until the introduction of MPi ran a ballast system of some sort. I think Rover use a 9 volt version of the system though instead of 6.
If your car was fitted with an electronic ignition then the amplifier pack will have required a 12 volt supply which is seperate from the ballasted supply to the coil (if your car does have ballasted ignition). So if when removing the electronic ignition you have accidentally connected the coil to the 12v feed instead of the ballasted feed you will be running 12v through a 9v coil which is enough to overheat it.
That is if your car has a ballasted ignition. If it's a ballasted coil you have it will say so on it (it will be marked 9v or ballasted or something like that).
Rover started to employ the system in their cars in the late 70's and most Mini's from the early 80's until the introduction of MPi ran a ballast system of some sort. I think Rover use a 9 volt version of the system though instead of 6.
If your car was fitted with an electronic ignition then the amplifier pack will have required a 12 volt supply which is seperate from the ballasted supply to the coil (if your car does have ballasted ignition). So if when removing the electronic ignition you have accidentally connected the coil to the 12v feed instead of the ballasted feed you will be running 12v through a 9v coil which is enough to overheat it.
That is if your car has a ballasted ignition. If it's a ballasted coil you have it will say so on it (it will be marked 9v or ballasted or something like that).
#7
Posted 04 March 2005 - 02:50 AM
You can also check to see if a coil was designed for a ballasted ignition using your volt/ohm meter. If you disconnect both low tension wires and connect your ohm meter across the (+) and (-) coil terminals, a "standard" or 12v coil will measure close to 3 ohms. A 6v or ballast coil will read less, typically close to 1.5 ohms.
BL cars are the only ones I've seen that use ballast resistor wire from the ignition switch to the coil. Most cars from the 70s and 80s that I've seen (from Japan for example) use a ballast resistor mounted to the side of the coil. From memory, isn't the BL resistor wire "pink" as opposed to the full 12v coil supply wire which is "white"?
BL cars are the only ones I've seen that use ballast resistor wire from the ignition switch to the coil. Most cars from the 70s and 80s that I've seen (from Japan for example) use a ballast resistor mounted to the side of the coil. From memory, isn't the BL resistor wire "pink" as opposed to the full 12v coil supply wire which is "white"?
#8
Posted 04 March 2005 - 10:55 AM
Thanks all, problem now solved. Moral here is...never assume you have wired things up correctly!
Steve
Steve
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