Humber FV1600 - ARN 105-819 - Restoration moves forward.

[Dave Mills]

After a little bit of head scratching i have overcome the miss/hesitation in the B60. First i dismantled the spark plugs and cleaned the carbon deposit from the ceramic insulator. After i have raised the compression ratio from 6.4 to 7.1 with a motor overall it is pushing carbon past the internal seal. Took it for a drive a little better but not fixed. Second, i removed the screw connector in the coil high tension lead and spotted a lot of carbon dust in the thread and around the internal contact - blew out with air, cleaned and refitted, test drive, better again but not fixed. Finally i rechecked the spark plug gap as it is opened out as i have electronic ignition fitted. Readjusted gap by eye making it slightly smaller. Test drove and i have a new truck - all fixed.

I believe it was a series of symptoms causing the problem with the main culprit being to wide a plug gap. Under pressure and torque i think that the spark was partially extinguished across the larger gap by the increased compression.

Well, that's my theory for the problem.

Dave.