I am rebuilding my 1972 1800. It has a B20E engine. I rebuilt the engine myself and replaced all of the components including valves, pistons, cam, injectors, sensors and wiring. Once reassembled, the engine started right up. However, I continue to have a miss on the #3 piston. I have checked the valve clearance, the fuel injector, the firing order, the spark to the plugs and have checked the electronic controller for electrical continuity. I still have the miss. When I remove the plug, it is not gasoline fouled but it is covered with a black soot.

Any suggestions?

Thanks.

Wwihtout knowing what you did to check the injector, I'd say swap it to another cylinder and see if the miss follows it.

Where I came from black soot = gasoline fouling.
Black & oily = oil fouling
--
George Downs, Bartlesville, Oklahoma, Central US

Could possibly be something as simple as dist. cap or plug wires.
It happened to me once after a rebuild with the same symptoms.
Turned out to be a brand new wire that was no good.
Good Luck