I have a 1983 ford van with a 351 engine. The standard
plug is a ASF42C. The last 2 times the van started acting up I looked at the plugs first and they had the black sutty look, which indicates a possible need for a hotter plug. Before spending
money on new electrics i would rather first try a hotter plug.
Please give me a suggestion on what plug would be slightly hotter so I can give that a try first..
Thanks..

 

Welcome to FTE!!!

Instead of going to a hotter plug, I would try and find why it is
running so rich.

 

It's running rich because that is the only way it will run.

 

Scarl, you need to find the route cause problem your truck
has. Something has to be wrong with it, if it will only run
rich, like you are describing...

 

I agree, fuel is getting to expensive to be wasting it. What type of carb do you have? It might need a rebuild.

PS If you have been running it very long like this, your catalytic convertor is probably ruined.