If you are not driving the car, only letting the engine idle whilst you work on it, the plugs will become black and look fouled. The engine needs a good run to clear out all the rubbish that has gathered whilst it has been standing and running at idle speeds.checked the spark plugs and they all dirty again
The correct timing for that engine is 12 degrees. You can go to 15 degrees but it should not be less than 12.we did the timing and left it aroun 7 degrees
These carburettors can be tuned but it is not recommended as a DIY job because it should be connected to a CO meter. In fact in some countries the adjustment is be sealed to stop the 'handyman' from interfering with it.
An Air Mass Meter is for fuel injected cars.
The easiest way to test the vacuum on the distributor is to pull the pipe off then increase the engine revs slightly above idling speed. Hold the revs steady and put the pipe back onto the vacuum regulator. You should notice a slight change in the engine speed.
Bill.






