HOME and how to join Forum Open Area General Scott topics Ignition Timing On 1930 TT Rep Re: Re: Ignition Timing On 1930 TT Rep

#13730
BRIAN MARSHALL
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I have always found it easier and better to set the timing as :- Points just beginning to open at 5/16″ before Top Dead Centre on Full Advance, or slightly less for longstroke engines. Just think about it…. A magneto sparks just as the points begin to open, and that is easily found with a magneto timing light. Also that original advice was for ‘new’ unmolested magnetos. Many have been modified over the decades to give more retard, in the hope of achieving a slower steadier tickover. Do you know how many degrees there are between full retard and full advance on your magneto ?
Few magnetos have the cam lobes at exactly 180 degrees apart, and I have found that BT-H and Bosch mags are better than Lucas in this detail. Always check the timing on both cylinders to make sure that one isn’t over-advanced. Running over-advanced causes pre-ignition/detonation/pinking, and that breaks cranks….
Brian