Hercules ZXB Pos or Neg Ground

[Jerry]

Hi All
I have a Hercules ZXB mounted to a O'Keefe & Merritt Generator Unit. My question is would the Hercules be a Positive or Negative Ground. It has a distrubutor Ingnition. I would also like to find a Parts manual for the Engine.
Any help would be appreciated.
Thanks Jerry

[enginenut2]

Jerry, The starter doesn't care about which polarity you have and the generator will charge either way you polarize it.The coil will work either way but the experts say it works better with the correct way.If the coil terminals are marked pos and neg you have a clue but if they are marked dist and sw you can tell if the polarity you are currently running is right for the coil by: 1)take a wooden pencil with the graphite center exposed a lot on the end 2) start the engine and pull a plug wire off the plug terminal and make it jump sparks to the plug terminal 3)place the pencil "lead" in between the wire end and the plug terminal so the spark jumps to the pencil then on to the plug and observe that the spark will look different from one side of the pencil to the other.If the spark on the side near the plug has a "flare" like look as compared to the spark on the side near the wire the polarity of the COIL is correct--if reversed it is wrong-but is this the original coil?Most military generators have a wiring diagram posted inside the panel--it should show the charging system wiring.If you can determine the generator's model and other descriptive information and pose this question on smokstak's generator forum someone will come up with a diagram to match.My guess is that it will be pos ground.

[Jerry]

Hi Thank you for your Help I took a look at the coil and the Positive side runs to the Points and the Negative side runs to the Ign. Switch. I also assume that it would be a Pos ground. I hve not got it running as yet but hope to get it running this weekend. Again Thank you for your Help Jerry

[KidDynamo]

I have a ZXB engine from an M-5 military generator unit and I have a manual. The manual states that the unit is negative ground.

I'm not sure, but suspect your coil should be wired reverse of what your post states, if you were to wire negative ground.

I once bought an old Cornbinder truck that was incorrectly hooked up positive ground and had run that way for some time. I reversed polarity, repolarized the generator, and then ran it for several more years.

I don't know the rock-bottom design of all the components enough to know if there would be long-term issues of running with polarity reversed from what the book says but at least my Cornbinder matched my other Cornbinders and what the book said was correct.

[John Schwiebert]

Also look on the generator's voltage regulator. If it is a Delco they were marked pos for positive ground and Neg for negative. If you publish the numbers they might be found in an old standard units book. A lot of generator equipment was positive ground. I also believe the Military wanted the military units Negative ground and that is why automotive alternators became negative ground. I don't remember how Auto-Lite systems were marked.

[Hootis]

Postive ground in my 1939 Toro. Got a manual on-line. YT tractors I think.

[bubbadt]

Jerry, I just aquired a genset, it has what I believe to be a
herculese zxb 4 cyl engine with an o'keefe/merritt gen.
I am having a problem with the numbers on the units, do you
happen to have any photos of your system.
This one has 3 phase-220v and 110v.
would appreciate any info.