If experience comes from making mistakes the KD3-1 has given me more experience
than most projects. Swapping in another bottom cover and trying a couple not
quite good enough to use crankshafts proved the problem was with the original
crankshaft.Using lathe to thin diameter of bottom cover just wasted
the part as it is now sloppy. A good replacement is in parts bin so that is not a problem. It is missing the hex thrust bearing for the bottom cover.
I do not have or if I do it is in hiding.
The story the powerhead tells is that the crankshaft was bent probably by taking a dive while running. The powerhead was taken apart and the two upper crankshaft
bearings replaced by a single bearing which allowed the crankshaft to turn freely
despite distortion. When I pressed in the correct bearings and tried to assemble
the distortion in crankshaft could not be accommodated.
Several options present themselves: look for a good postwar single crankshaft...
that could be a LONG wait, swap in a KD3-2 (Bendix Magneto) powerhead OR take
crankshaft out of KD3-2 and use it to build up KD3-1

This is the first experience with a bent crankshaft. Usually the issue is corrosion, wear or worn spline socket. I give the junk crankshaft to shop class
to practice O.D grinding. If anyone needs a crankshaft to build a nonrunner
K Model single or KF3 or K Model twin I have several taking up shelf space.
After Labor Day they are going to school.
Louis

Straightening a bent crankshaft is a touchy issue. A friend in small engine
business had a tool to do that BUT for liability reasons he would not
do it for public.

The early small K Models on back burner for moment.
Attended an outboard club meet Saturday. A fellow I did a favor for gifted me with a Mercury KF7...well not exactly...items had been removed and it looked like a salty but was assured its condition was from being left in a wet boat house for many years.
Separated tower from powerhead. Tower looked promising after cleaning and rolling over prop shaft.
The powerhead was another matter. I noticed the Champion spark plugs were J7
and J11 which raised suspicion motor had been ill before it was hung up.
When flywheel came off I noticed half the ignition had been removed prior
to many years of corrosion. Another sign motor had problems that took it out of service and were not repaired. At the moment powerhead is mostly stripped down
except for exhaust cover which was left alone because 3 screws were stuck.

New to me technique: used Dremel tool with abrasive cutoff discs to cut long
slot in key that could not be removed by other means. The slot was not deep
enough to go thru key into keyway so no harm done to crankshaft. Stuck key
was then driven out with nail set used as punch and small ball peen hammer.

Although I intend to complete tear down of powerhead it is likely as bad
inside as it looks outside. I am awaiting a friend to return from "Up North"
to advise and assist as the larger Mercs are more his flavor than mine.

I have been looking into subject of straightening crankshafts. Not sure if
it is something I can handle. A set of V Blocks needed to test and determine
high spot of run out.
Louis .