MG Car Repair: 79 MGB running rough, momentary thing, excess fuel

Question
I have a 79 MGB that I just replaced plugs, wires, cap and rotor on about a month ago. I drive it about once a week. I noticed two weeks ago that it seemed to hesitate on acceleration at highway speed. This was a momentary thing. I drove it today, however, and after about 30 minutes of driving on the highway the car began to hesitate and run rough on accelaration. During the rough periods I noted smoke coming from the exhaust (possibly white but it was dark out and difficult to tell for certain). Toward the end of the drive the car was idling ok at a stop but acceleration in first gear resulted in weak acceleration and rough running as well as some smoke again.

I have not yet done a compression test (am on a trip right now and will do so when I return). Is there anything else I can or should check? I did NOT adjust the gap in the distributer when I changed the cap and rotor. Would that have anything to do with this? It is a 4 cylinder with the Fireball electronic ignition. I want to check the timing as well but do not know yet if there is a timing advance with this ignition and so do not know what do disconnect to do this properly.

One other thing to note: It seems to me that the dash lights are dimmer than they were before. My turn signals operate slower as well. Would the alternator have an effect on this problem? Maybe I should have it tested as well...

Answer
Hi Brian,
All your symptoms are useless to determine what is wrong other then to tell you something is wrong.

The only way to find a problem with the way an engine runs is to test.
The compression test is the first test. The smoke may be a good clue but you need to run it in the day light so you can see the color of the smoke. Black smoke is excess fuel, Blue smoke is oil and white smoke is either coolant or brake fluid.

The best tool is a oscilloscope if one is available to you. If not you can do other things like test the fuel pressure at the carburetor (1.5 to 3 PSI) and examine the spark plugs to see how they are colored. Flat black is excess fuel as is the black smoke. Glossy black on only one or two plugs means a fouled plug for either an electrical problem or a combustion chamber problem (compression test should have shown that)
If one or two plugs are fouled you should check each plug wire with an ohm meter and clean or replace the plugs and examine the cap and rotor for carbon tracking.

The charge rate will not usually effect the ignition unless you have a bad diode in the alternator and AC current is applied to the ignition system. A volt meter across the battery should show any problems. (Should be 13.8 to 14.5 v at a fast idle)
Howard