[dfkrug]

Castaway:

I am a bit surprised that your 1070 has a balance shaft, which is designed
to counteract some of the rocking and/or rotational vibrations. At only
about 2-liters and with the heavy flywheels I see on these tractors, I
would not expect a balance shaft. The 3-cyl JD motors don't use them
and they are not as inherently balanced as a low-displacement 4-cyl is.

Anyway, I think RobJ has hit on the reason. The new engine you
bought may be designed for a different application. You did not say if
it came with a flywheel. Maybe the intended application is something like
a generator where some additional vibration is more tolerable?

If your new engine DID come with a flywheel, my inclination would be to
use it as-built. The old engine's flywheel may not work well on it.

(As and aside, I have not had a problem finding a machine shop to
balance a crank, one-cyl or 6-cyl.)