The first thing to check in order to fix the misfire, was the ignition system.
The obvious place to start was the ignition leads. I have replacements on the way, but in the mean time I needed to try to insulate the existing ones. Electricity/Spark has a great habit of taking the path of least resistance, so if it is easier for the spark to go anywhere BUT the spark plug, that’s where it will go.
The previous owner kindly left three of the four boots on the dash, so I greased them up and slipped the boots on. The lead that I didn’t have a boot for I tried to insulate with insulation tape. These leads are only temporary.
I also checked the spark plugs. They don’t look too bad, but the gap was massive. They were all over 1.1mm, so I gapped them down to the commonly used 0.8mm (manual calls for 0.6mm but that is crazy small). Plugs One, Two and Four were all the same colour as below, but plug three was dark and a little sooty.
The cap though, is well past it. There were a lot of deposits on the terminals, and the terminals are badly pitted. I cleaned as much as I could off the terminals, but they aren’t going to be helping anything.
I’ll order a distributor service kit, to replace the cap, rotor, condenser and points.
I took it for a test drive after this little service, and already there is a noticeable difference. The misfiring has lessened a lot, and it runs smoother. It still isn’t idling perfectly, and the misfire is still there, so I still have some work to do. The exhaust leak wont be helping and I bet the carb is filthy.