This SOB of a problem has got me stumped.

Background: Mark 78 converted to late model electronic ignition. Rebuilt the motor over the winter and fired it up. Motor started instantly, but it was running rough, smoking (had lots of oil in the cylinders) and idling at 3K with the throttle set to idle.

What the hell?

Distributor’s gotta be off a tooth, I predicted, but it wasn’t. I then backed the idle stop screw off a TON and fired her up again. No difference!

What the hell?

The carb butterflies gotta be open somehow. Checked and readjusted, fired it up and—no difference; still running rough and screaming at 3K.

What the hell!

Having nary a clue as to what was going on I started messing with the idle adjustments—I had to try something. Still no difference.

While I trying to figure what on earth to do, it suddenly smoothed right out and dropped down to a nice 1K idle.

What the hell!!!

From my 60 years of messing with motors, I've never seen a screw up of some kind (fuel or ignition) cause a motor to rev HIGHER; lower is normal.

The next day I took it to the river. Started up fine, then did the high, rough idle thing again. Rapped the throttle a few times (and good!) and the little b*st*rd suddenly dropped to a nice, 6 cylinder idle at around 1K. Snicked it into gear and she took the gas immediately without a hint of a bog. Ran the boat then and she ran normally for the rest of the day.

So what on earth is causing this crap! I'm at a loss. Thought it might be the switch box (somehow) so I changed it (and the coil late). It was running normal by then so I THOUGHT that had cured it, but the problem returned when I took the boat to the river.

Any suggestions will be gratefully accepted.

Jeff