185 hp Johns. spark plug ????

[mako 201]

My 1985 815 hp Johnson currantly has AC M40FFX plugs. They are gapped at about.042. Is this the correct gap, and is there a better plug for my motor.

 

[Joe Reeves]

Re: 185 hp Johns. spark plug ????

Mako 01..... The plug you have is a AC interchange for the Champion QL77JC4 or L77JC4 s/plug. Any of those plugs should be set at .040. The better suited plug for your engine would be (in my opinion) the QL77JC4 plug. The "Q" indicates a resistor plug.