05-04-2022, 02:57 AM
(04-04-2022, 02:18 PM)John H Wrote: FWIW, our chummy (fitted with a DJ distributor) requires a points gap of about 20 thou to get the required 50 to 60 degrees of dwell (measured with a proper automotive dwell meter). The engine runs very badly with the recommended gap of 12 thou. The cam lobes are not obviously worn out, but I've found that using a dwell meter is the only way to set the points up properly, at least on this particular distributor.
This is the correct and proper method imho for any distributor regardless of number of cylinders or its mechanical condition. It is a good simulation of actual operating conditions. To speed the process, what we used to do is adjust to the low end of the nominal dwell setting while motoring the engine on the starter motor (obv. you crank handle aficionados cant do this) with the main HT lead from the coil shorted to earth (or a gap type spark tester attached) and the spark plugs out. Then reconnect everything, start the engine and after a short idling period (5 minutes or so) readjust to suit, remembering always that dwell angle has an inverse relationship to points gap.