I can’t take credit for the tip on starting a Perkins with a low battery.
However, for the 3GM30F, there is a place for using the hand crank to start
Remember, since this is an optional accessory, if you didn’t ask for this
feature when you purchased your new 3GM30F engine, you may not know what to
look for. Look just above the crankshaft pulley, you will find a dome
shaped sheet metal cover with two opposing ears at its mounting flange and
two Phillips head screws retaining the cover to the timing cover, the dome
is about an inch in diameter. Remove the two screws and cover, you will
find a small 1/2" diameter shaft protruding through the timing cover seal.
This is where the hand crank goes, however, as an option, you are missing
the pin that slides through the side of the shaft which engages the hand
crank and you also need the Allen headed set screw which secures this pin.
Once you secure the hand crank, pin and set screw your in business.
— Marty Chin