Hello All:

1967 Volvo 122S Wagon. Twin SU Carbs. Pretty much bone stock. I did a tuneup last weekend including new plugs, points, rotor, cap, condensor, fan belt, etc. and did all of the usual including setting the timing advance, points, gapping the new NGK plugs (.030") set the valves for about the 100th time and changed the oil, oil filter, fuel filter, air filters, etc. I did a "make and break" of all major electrical connections and gave everyone a light smear of dialetric grease. I asked Wendy how she was driving after the tuneup and she said "unchanged" like that was a bad thing.

After a week of basically local driving with the occasional highway jaunt I pulled the plugs to check how we are doing and found the strangest thing - the plugs from odd-numbered cylinders are dark, almost black with just a hint of brown, and the plugs from even-numbered cylinders are pretty close to white with just a hint of brown. The metal circular edge on those plugs is black so I know there is ignition in those cylinders.

Now I can understand plugs 1 and 2 looking the same but different than plugs 3 and 4 - obviously that would be a carb-setting issue. I can even understand plugs 1 and 4 looking the same but different than plugs 2 and 3 due to some weird blockage in that part of the exhaust manifold but this one really stumps me.

Just to check my math I re-checked the gaps on all of the plugs and checked the valve lash again - everything checked out. Any ideas kids?

Cheers,

Jeff Pucillo