My '67 truck has a 250 with Clifford intake along with Clifford shorty headers and an Edelbrock 500cfm carb. I've always had a problem with the 3 and 4 cyl's being too rich and fouling the spark plugs to the point that they become crusty and coated with brownish gunk and I have to clean them now about once a month. All the other plugs look fine and have a nice tan color to them with no build-up.
When I first bolted on the carb I tried different jets and rods using the Edelbrock tuning instructions, but never had good luck except with the stock jetting and rods. I've also tried the carb turned 90* to no avail.
The truck runs great and idles well otherwise. Anyone got any ideas?
