The secret to hand cranking is how you hold the crank. Never have your thumb on the other side of your fingers, that way when it kicks back it will pull out of your hand and you will automatically pull your arm out of the way when the crank comes back around. I have hand cranked my 1937 car with a 216 engine, also hand cranked my uncle's Model "T" Ford (sorry) many times using the thumb placement above and never had a problem.
