By Peter Cook (NSW)
Readers who were at the ECM know that the ’25 misbehaved after arriving at Macksville on Sunday. She’d run really well for 500kms but, in sight of Macksville bridge, she lost power and started to miss. At first, I thought it was vapour lock, but some of the noises were very concerning. Anyway, we limped into the showground and suspicion was cactus cam gear (again)! She’s signed up for ritzy NRMA treatment and the young NRMA guy agreed that she needed a tow. Long story short, she arrived back in Sydney at 11p.m. Tuesday night.
So, the first job is to confirm the diagnosis. Removing the inspection cover, I expected to see a mass of aluminium filings and broken teeth. But no, it looked undamaged and with plugs out it cranked over smoothly confirming it was good all round. BTW the plugs were all black with carbon, whereas in recent years they have been the happy biscuit colour.
So, suspicion of front shaft bearing was unfounded. More investigation required:
1. New plugs still won’t start.
2. Cranks smoothly with ignition off.
3. When ignition on cranking hesitates and makes a noise.
4. Checked gear on bottom of distributor…all good.
5. Replaced complete distributor with spare….no change.
6. Replaced coil with spare…no change.
Colin Castle came over and we went through it all again this time also checking spark on each pot. Seems okay then Colin looked at the distributor cap (as I had also done). He saw the fine cracks which I didn’t notice.
Apparently, the high voltage inside the distributor will track through the cracks.
AI says: ”A cracked distributor cap allows high-voltage electricity to arc to ground instead of reaching the spark plugs, leading to engine misfires and rough performance”.
But, in my case, it looks like it was sending spark to number one and five at the same time. And possibly two and six were getting the double shot as well.
It’s always the long haul trips that bring mechanical issues to the fore. This time, we guess the long warm run opened up the cracks enough to crystalise the weakness.
As a side note we got to travel in a 1983 Convertible, a 1955 Coupe and a 1950 Convertible thanks to John Stewart, Gary Ferrett and Castles (all the way home).
Special thanks to Colin for his help and knowledge.