Reply To: 1941 Merc KB-3 Point Setting Vs. Coil Swap

[Buccaneer]

billw wrote:

Interesting. I guess if it were me, I would pull a known-good conventional carb and reed plate off one of my KD3s, and see if it would stay running on that. That way, you’d know whether it was the poppet valve rig or the crank case. I have a poppet valve, Montgomery Ward/Merc, that is very similar in design. It says running okay but it has a weird behavior. It will be running strong, then drop to half speed, then come back strong, just EXACTLY as if it were a two-cylinder engine, dropping one cylinder in and out, like turning a switch on and off. I can’t imagine what does it; but it’s the only one-cylinder, Merc-based engine I ever had that did that, and it’s my only poppet valve Merc.. The point is, I don’t fully understand or trust the run-ability of those simple valves. My only other thoughts are, that you don’t have a ton of spark advance there…I know it’s not on a boat but I would still try a little more advance. Also, where is all the smoke going??? I see none in the video. Those things have to have 16:1, in my opinion.

I have the KB-3 ‘s cousin on the workbench now, and it’s
a KB-1A, “no thrills” version, that has the reed plate
and conventional Tillotson AJ carb on it.

I’m not sure though if the reed plate will go on the KB-3.
The garage is warming up now, but I’ll find out soon.

I tried moving the mag plate all over, and about 2/3 rd’s
advanced seem to run it best.

It had 16:1 fuel mix in the tank, and I gave it a good dose
of 8:1 to richen it up. I wondered about the “lack of smoke”
myself…….. I usually have to evacuate the garage after 30
seconds! Maybe the 20+ below weather has depleted
the oxygen level!

Prepare to be boarded!