Two things you missed especially if British car...Lucas...Cheaper rotors will give problems and coils do fail to work properly.I had an issue...motor woud stumble like carb issue but saw tach going crazy.Changed coil and problem gone.
Yes coils do fail. I had an intermittent miss in my MGA that I couldn't seem to fix. It seemed worst under load or in damp weather. (Not real common in southern California, but it happens.) Finally one dark evening I had the hood up with the engine idling and I could see the spark tracing down the coil tower. There was a tiny hairline crack in the coil tower, barely visible but enough to conduct the spark at least part of the time. A new coil eliminated the intermittent miss.
Good points sir_mike. I would still add the use of an adjustable spark tester to see how good is the ignition systems performance (coil + points + voltage) and on the other hand how good is the insulation of the rotor, distributor cap and even igntition cables. The best to use was Gunson Flash Test which was showing by color scale if the igntion performance is good or if there is someting to be repaired in the system. Unfortunately Gunson Flash Test is not anymore available but with a modern adjustable spark tester you can do the same.
One of my friends rolled his racer off the trailer, and it wouldn't start, no matter what he did and all the wiring checked out. Then someone noticed the distributor cap was missing the carbon center contact! We were 20 miles from the nearest town, it was a foreign car and it was Sunday... A temporary fix was whittled out of the carbon center from a discarded 'A' flashlight battery and saved the day for him.
You'll need to log in to post.
