spark plugs

[Kurt in NJ]

My 3X plugs amortized over 30 years are cheap, the car runs better than when i was using other plugs to "save" them, if I want to burn them white I close the GAV ( exhaust emissions on loaded dyne, 18 mph in 2nd, CO 0.15, HC 60 ppm)

 

[Larry Brumfield]

Larry, does the choice of gasoline make much difference for the plug choice? I typically run Premium gas, because our local gas station offers the non-oxygenated gas in Premium grade and I avoid the ethanol that way. I know it reduces knocking/pinging, but never thought about heat-range for plugs.

Makes no difference that I have seen. Most grades of commercial gasoline will produce the same light brown to grayish tan color on a plug running at the correct temperature in a good engine.

Now the ethanol in the gas is supposed to produce a less rich mixture but I've seen no effect on the plug color. Many Model A's are running rich anyway.

Larry B.

 

[Mitch Bunkin in PA]

I use W-18 because FordBarn posts in '08 and '09 said they're close in performance to 3X. Les Andrews has photos of spark plugs in his book showing different conditions.