MG Car Repair: losing spark, air gap, first test

Question
I have a 1977 Midget that runs fine but stalls after getting up to operating temp. loses spark let it sit for a few min. and will run fine again for just a few min. i am sure of the lack of spark just not sure why any ideas thank you for your help

Answer
Hi Dave,

When you loose spark after warm-up, you need to run a few small tests.

All tests MUST be run in it's failed mode. (when there is no spark)

First test to see that you nave 12v to the coil with the key on, then feel the coil to see if it is overly hot. (too hot to leave your hand on it) An over heated coil can fail when hot and start operating when cooled off.

Check the air gap at the pick-up in the distributor. (.012" to .015") Check to see that you have power at the white and the White w/blue tracer wires going to the igniter (if you still have the original Lucas ignition.

If you have power where you are suppose to and the coil is not over heating, it is usually the igniter on the distributor that is failing.

Howard