MG Car Repair: MGA loses power and runs rough as I raise RPMs, distributor shaft, point gap

Question
I was riding in my MGA and it was running great when it lost power and started to run rough. I reset timing, values, and carbs. It starts right off the bat and idles like a dream but when I give it gas it gets rough and acts like it is missing on two cylinders. The car does have an electronic ignition.Any ideas would be of great help.

Answer
Hi Lance,
Set the RPM to a speed that it is missing and hold it steady and short each spark plug out with a screwdriver or such and note the RPM change to establish if it is a cylinder or two or all of them. This is called a "Cylinder Kill Test"
If it is two cylinders and it is either the front two or the rear two spray some fuel like starting fluid into the intake of those two cylinders to see if you get a big RPM change. If it revs up than something is wrong with that carburetor and that carburetor must be gone through. Check the spark at any dead cylinders that were noted by the "cylinder kill" test.

Remove the distributor cap and examine the inside and outside closely for "carbon tracking". check the distributor shaft for loose play and check the point gap on each cylinder. (this checks for a bent distributor shaft) The gap should be close to correct on each lobe. (.015")

If the copper plug wires were replaced with carbon resistor wire you need to test each wire with a ohm meter. If you still have the Lucas resistor ends on the copper wires you need to try switching them around to see if the dead cylinder follow the wire ends. They can be tested with an ohm meter also. As i remember the ohm value is written on them.

Check the valve springs on the dead cylinders to see that they are not broken or weak.

Let me know,
Howard