MG Car Repair: MG starting problem, bright sun light, starter fluid

Question
I have a 1977 midget that was cranking fine for quite a while. Now the starter cranks strongly, but it wont turn over.  I get the feeling that it is not getting a spark.  

What kind of tests can I run myself to determine whether the spark plug is sparking and getting a blue color.  

I tried to start the car with starter fluid, but it still didn't turn over so I assume I have an electrical problem not a fluid problem.

Please let me know what steps I should go through to determine the problem.

Answer
Hi Ray,

You are confusing me so we need to get our terminology in sync. When you say "The starter cranks strongly" I take it that you mean it spins the engine strongly? But then you say "but it won't turn over" which to me says the engine is not spinning at all?

Do you mean that the starter spins the engine over strongly but it won't fire off or start running?

To test ignition just remove one spark plug and attach the plug to the end of the plug wire and lay the plug on any metal part of the engine. Then have someone try to start the engine with the starter motor. As the engine spins over the spark plug should spark and it should be blue in color (not in bright sun light) and it should be a thick spark (about as thick as the lead of a pencil.) If there is no spark or the spark is thin as a hair and orange or yellow in color (not in bright sun light) then you do have an ignition problem.

If you used spray  starting fluid into the intake when trying to start it, that is another conformation that you have an ignition failure.

There is a series of tests that you can do at home to try to find the fault.

First you need to ID the type of ignition system you have. The original Opus/Lucas failed so much it is unlikely you still have that system so remove the distributor cap and see if there is any markings on the unit inside or if someone has installed points and condenser in it.

Several aftermarket ignition systems were available over the years. Most have their name printed on them. They do all share one thing though. You must have 12v available to the (+) side of the coil with the key on.

Look for a name on the system and let me know and test for power to the coil with the key on.
Your engine is a 1500 Triumph Spitfire and several different distributors were available for it. Let me know and I will see if I can guide you further.

Howard