• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Ignition woes... melted the points

Share this page

Strapping_Lad

Strapping_Lad

Member
Offline
Well I have my new alternator in finally and all the positive to negative ground check list done. All I needed to do was put in the points, set and start. Initially the ignition light came on and all was well. Tried to crank it over and would not start. It sounded like it wasn't even trying to fire, just the starter going over and over. I tried to start it maybe 2 or 3 times with holding the key for 3-4 seconds each time. I left the ignition on for maybe 5 seconds and the dizzy started to smoke. There was also smoke coming out of the plug wire from the dizzy cap to the coil and the wire melted that gives power to the tach on the positive side. The wire from the ignition switch is also on the positive side of the coil but did not melt. My points were connected by a single wire to the negative side of the coil. What could be the cause of the points melting?

The coil in the car right now is a Bosch Blue Coil (Made in Germany) looks pretty old. This is the same coil that was running my Pertronix positive ground before I made the switch. There is no ballast resistor hooked to the coil and since it ran the pertronix without one I can only assume it is internal.

From what I can gather, there was a burst in voltage through the coil causing the points to melt, but this would mean the internal resistor in the coil would have to fail as well as the condenser in the dizzy. Would the coil still produce voltage even if something internally, such as the resistor, were to fail?

What did I miss here?
Could the coil have just bit the dust and decided to take my points with it?

I made a diagram of how everything is connected at the moment.
Untitled-1.jpg
 
Make sure the stack up of the ignition wires and the plastic bushings is correct on the points. The wires should be inside the bushings against the spring that attaches to the movable point contact. If it is not you will have a direct short to ground.
 
Did you convert the tachometer to negative earth,as this wire melted ,it would seem that there lies the problem as this would melt by going directly earth
 
I did convert the tach following instructions by John Twist and from the mgaguru.com website. That was pretty simple to do, but I could have hooked the wires backwards to the tach, if its possible. The white wire in the back of the tach is suppose to be spliced and relooped along with resoldering a diode and small wire. Even if the tach wasn't connected right, that cause the coil to melt my points... could it?
 
Strapping_Lad said:
Even if the tach wasn't connected right, that cause the coil to melt my points... could it?
Click to expand...

I think you're right, the tach isn't the cause.
 
If it happened that quick then it sounds like either you bypassed the coil or it has a dead internal short. Even a wrong type coil would not burn points that quick.
 
I've been tracking down the wiring around the car and all looks to be correct. The guess I can come up with is even after carefully putting the points on, I managed to get a short from inside the dizzy because of my lack of experience with assembling points. :p
 
I must have missed it but you did put a condencer back in. Won't run without it.
 
Back
Top