My neighbor has a '67 122S. The car starts after much protest but is low on power.

The first time that I looked at the car, it cranked very slowly, so I swapped in a battery from one of my other (non-Volvo) vehicles that happened to be about the right size. Lethargic cranking problem solved, but it still sounds 'weird' in some way when trying to start.

It will start after cranking for a good 10 seconds. I should mention at this point that the engine is a B18B. No smoke. A faint fuel smell that goes away when it has been on for half a minute. Lots of clicking from the engine. Sounds like the fuel injectors on an LH-Jetronic car, but about 5 times louder. Valve train noise or...?

It drives okay, but is unresponsive.

We replaced the cap, rotor, plugs and plug wires. I have no idea how to adjust/replace the points and condensor. Something tells me that wouldn't make much difference, though.

I am thinking: timing, carbs, or - given the clicking sounds coming from the engine - valve train issues. Or a combination thereof.

Where should we start?

Thanks.