QuestionHi Howard! My '76 MGB is having an ignition problem. When I start it, it runs for a few minutes and dies. Once it dies, if put a dwell meter on it, it stays at 90 degrees when cranking. I've popped off the distributor cap and tested contacts without seeing any obvious culprit. Then, after a few minutes or a few hours, it starts working again. It'll then run for a few minutes before quitting again.
I recently, but not just, replaced the points, and I'm inclined to suspect the ignition coil due to the intermittent behavior. Can you please tell me the proper procedure for diagnosing this? We can assume that the problem stays around long enough to complete a test.
Thanks!
AnswerHi Billy,
The coil or condenser are the most suspect with your symptoms. First test the coil to see that it is the correct coil. It should be a low ohm (6v coil) and it should be powered by the resistor wire with the key on and powered by the starter solenoid directly in the start position. If it is powered wrong with straight 12v all the time, then this would cause the coil to over heat and fail until cooled off.
Test it this way, turn the engine by hand until the points are closed and turn the key on and check the voltage at the (+) side of the coil. It should be low as 6v or as high as 9v. If it is higher than that then you have the ignition system wired wrong. This is assuming the points are clean.
With the ignition turned off and the wires removed from the coil (+ & -), test across the positive and negative terminals with the volt/ohm meter set on low ohms. It should read about 1.5 ohms.
Also when you set the point gap, do it with a feeler gauge at .015"
let me know the results of the tests.
Howard
