Topic: How simlar are the 74 and 77 550 motors?

[d3buttz]

I have two 550 motors.  1 seized 77 and one 74 that upon inspection had metal in the oil with futher inspection a chewed cam sprocket(could be worse as i get deeper). the question is-
Can i make one good motor out of both? is the parts interchangeability close enough to do it?

[73hutch]

certainly. they are all the same. my running 550 has a lower case off a 78 and a head off an earlier model.