Trevor:
The electronic ignition you removed had vacuum retard to control emissions.
This device actually makes the car run worse under light load but I
believe that it reduces oxides of nitrogen by reducing peak combustion
temperatures and pressures during cruise.
The vacuum advance should be connected to "ported" vacuum. This is a
vacuum port that is located just in front of the throttle plate. This port
will not supply vacuum at idle but will advance the timing once the
throttle is opened. When I made the conversion on my Spitfire, connecting
the vacuum advance directly to the manifold caused the engine to idle too
fast and unevenly.
To locate a ported vacuum supply, either look at the carb if you can or
connect a vacuum gauge to the available ports on the back of your
carburator until you find one where vacuum is reduced at idle. Mine was
located on the bottom of the mounting flange on my Stromberg 150CD.
As an aside, My Spitfire quit the second time that I ever drove it due to
the wonderful Lucas electronic ignition packing it in. My four year old
daughter was along and she wouldn't ride in the car again for a long time
after that. I only hope that it didn't scar her for life!
Good Luck
Bill Eastman
61 MGA
|