Getting this Generator to gen !

[Saskwatch]

Soooo -  I have had the generator apart, paid much more attention to carefully clean / shine up commutator than I did with the starter (thank you for the heads up on that ) . 
  Wanted to give it the “motoring test” as described in the shop manual , hooked the positive post of the battery to the generator rear mounting bolt , clamped booster cable to negative post of battery & was going to clamp other end to the armature post , when I did generator started turning immediately before I got to ground the field terminal (post closest to the engine block) to the generator case. …… was happy to see the generator “ motoring” but does this mean the field terminal is shorting out to ground & the generator will not operate properly ??

 

[D35 Torpedo]

It's probably motoring off residual magnetism. If the field was shorting out there wouldnt be any magnetism, and it wouldn't turn. Best to ohm out the field windings to ground and to the armature. That will give you a definitive answer.

[Saskwatch]

Thank you very much for your response Torpedo, unfortunately I’m technically challenged in all things electrical.??‍♂️ 
   To “ohm out the field windings to ground and to armature”, can I do that with a jumper wire on field post then touch other end of wire to ground and then to the armature post?