saf@bonnie.UUCP (Steve Falco) (11/22/85)
My '79 Chevy 305 V-8 recently started running rough under light loads - sort of a miss... I pulled the plugs to do a compression check and found two plugs had some white, brittle crud on them. One was so bad that the stuff had almost filled the area between the ceramic and the shell - it had also gotten into the gap. Ah ha! Here is the miss. I cleaned the plugs (which have under 10k miles on them - supposedly ok for the HEI ignition) and sure enough the miss went away. What is this white crud and what causes it? Oil fouling is usually black; could this be a deposit from BURNED oil? How about gas residue? (The car burns unleaded premium.) A friend suggested bad wires - this would cause a slight miss leading to a buildup of unburnt gas on the plugs. I am planning to change cap, rotor, and wires since the engine now has 50k miles on it. BTW, the compression was between 170 and 180 psi on all cylinders; does anyone know what the spec is? The shop manual doesn't seem to have it!! Steve Falco