Spark plug fouling- 1971 350 engine
Thread Starter
5th Gear
Joined: Nov 2013
Posts: 5
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Spark plug fouling- 1971 350 engine
What would cause the spark plugs to be tan half-way around the anode and oil coated on the other half of the anode? This is common to all spark plugs. Valve guide seals replaced last year, 2016. Piston rings condition unknown. Cylinder compression between 175 and 180 psi on all cylinders. Car runs decent and no discolored exhaust. I have tried different brands on plugs, have E3 installed now with same results.
Race Director
Joined: Sep 1999
Posts: 11,361
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From: Plano TX
Oil is making it past the piston rings, goes up into the intake during valve overlap and then back into the cylinder hitting one side of the plug. If your oil turns black very quickly after you change it, that's further indication of a ring issue.
That's assuming you checked the easy stuff like a stuck PCV valve.
Running a hotter plug and thicker oil will help.
That's assuming you checked the easy stuff like a stuck PCV valve.
Running a hotter plug and thicker oil will help.
Last edited by zwede; Aug 13, 2017 at 10:04 PM.
