Re: 9.9 Johnson Carb Question

[rudderless]

The 74,75,76 had a head that would spray intake charge right at the plug tip. Later heads had the deflector to keep this from happening. The 93 and up the plugs are aimed away from the intake charge. The older head was higher in compression so I use it. I only use the hot plugs on that head. I aim the ground electrode towards the intake charge in an attempt to shield the center electrode from the charge. The tip of the plugs are always black but further in they are running clean.

Shorten the ground electrode so it will pass by the center electrode at .025-.028in…kinda like a surface gap plug but with a ground electrode.

I am using red Atom point eliminators and really like them. If they cook I will make a couple like in the make your own Atom thread. They are mounted outside on the motor next to the spark coils.

I feel the ngk’s have a little less thermal mass at the working end and heat up quicker.

The bottom cylinder runs cooler, puts out less power. The upper cylinder drains condensed fuel into the lower cylinder and the upper has a much shorter intake runner. The cc reeds burnt on the upper much faster than the lower cylinder also.

I’ve only got 3 years onto this motor..members like Pappy have had a lifetime practically. He knows more than he lets on I betcha…