Why does my #6 cylinder spark plug foul in my '63 ford falcon?
’63 ford falcon futura convertible, 170 c.i. inline six, the #6 cylinder will sometimes get gunked up with what looks like oil, then she runs crappy. Once I change the plug she’s fine. It seems this happens with excessive idling, like rush hour. We haven’t pulled the valve cover off yet but my dad’s guess was: I guess there is a drain hole in the rear of the head that allows the oil to cycle down and maybe a rubber valve stem seat popped off and plugged it? Does that sound right? He explained it to me but I was lost.
o.k. I forgot to say I did a compression test: cylinder #1-150, #2-170, #3-170, #4-170, #5-170, #6 (closest to firewall)-170. Is that good? Why is #1 a little off but nothing bad happens to it?
One Response
mad_mav70
11 Feb 2010
Could be, but the #6 cyl is where the engine gets the vacuum from, check for excessive oil in the PVC valve. I’ve had the #6 cyl go bad before. As far as why the #1 cyl has lower compression, if you have some miles on the motor, the # 1 cyl runs the coolest. As engine temp decreases cyl wear increases.