01-26-2022, 09:11 AM
Good job Brandon, interesting about the no 1 plug being black.
The waist spark system is normally balanced as you know very well and i think you connected the no 1 plug so it would still fire no4.
The rpm dropping from 1050 to 900 would indicate one cylinder dropping out with fuel still injecting in no 1, could have been checked with a secondary ignition pulse on the no 1 spark plug lead with a scope on both no 1 and 4 to compare maybe? ( and you could see that one spark is positive and the other negative with regard to chassis, surprise! )
If the no 1 cap was faulty that would still affect the no 4 i think, ( reduced high voltage ) but like GO said if the coil had an internal path to ground on the no 1 side then you have the effect only showing up on no 1 cylinder.
Since the voltages are so high it seems hard to test this other than setting the coil up with two known good plugs connected AND earthed to the coil metal core plus one side of the primary winding for the same reason and slowly reducing the 12 volt supply until one plug quits?
Anyway good on you for getting to the bottom of this and thanks very much for sharing this experience, great style repair job
The waist spark system is normally balanced as you know very well and i think you connected the no 1 plug so it would still fire no4.
The rpm dropping from 1050 to 900 would indicate one cylinder dropping out with fuel still injecting in no 1, could have been checked with a secondary ignition pulse on the no 1 spark plug lead with a scope on both no 1 and 4 to compare maybe? ( and you could see that one spark is positive and the other negative with regard to chassis, surprise! )
If the no 1 cap was faulty that would still affect the no 4 i think, ( reduced high voltage ) but like GO said if the coil had an internal path to ground on the no 1 side then you have the effect only showing up on no 1 cylinder.
Since the voltages are so high it seems hard to test this other than setting the coil up with two known good plugs connected AND earthed to the coil metal core plus one side of the primary winding for the same reason and slowly reducing the 12 volt supply until one plug quits?
Anyway good on you for getting to the bottom of this and thanks very much for sharing this experience, great style repair job