Ford 641 12 volt conversion kit question

Good afternoon,
I recently purchased a 12 volt conversion kit from this website for my 641. In the instructions it says that some 600 series tractors wont need the orange wire from the solenoid to the terminal block. How do I know if my tractor needs this or not? The instructions don't provide any guidance.
What is the orange wire actually for?
thanks in advance
Jon Petersen

Jon,
If I understand this correctly, the early Ford tractors (NAA,600,700,800,900) used a Solenoid that only had 3 terminals. 2 BIG terminals and one small terminal.

As these were 6V Positive Ground Systems, one Large terminal hooked to the NEGITIVE post of the battery (power in). The second large post went to the STARTER. The small post went to the start button on the transmission case. You had to get the wires hooked up correctly, as the large terminal to the battery also provided power to the relay coil wires inside the solenoid.

You can tell if you have this type of solenoid, if you can push the starter button and the starter will spin WITHOUT the key being on.

Later, Ford went to a 4 post Solenoid. Two large posts were hooked the same. This solenoid had 2 small posts one to the terminal block (switched power side) (your ORANGE wire), and the second as before went to the start button.

When the key was on, the start button would complete the circuit and activate the coil in the relay (solenoid) to connect the 2 large posts together and provide power to the starter.

This change happened when the xx1 series of tractors came out which includes your 641.

Now your tractor being in the neighborhood of 50 years old and "fixed" who knows how many times could have any solenoid on it. 3 Post, 4 Post, Car, anything can be made to work if YA try hard enough! LOL!
Hope this helps!
Keith

Keith, thanks for the answer, I am pretty sure that it is a 4 post solenoid. 2 big ones and 2 small ones. I cant look at it as I'm not at the farm but I remember thinking that there is a post with nothing attached to it.
I don't believe the starter would turn over without the key being on.
I will hook the orange wire to the terminal block as noted in the directions.
Thanks again for your time
Jon

Keith you say NEGATIVE post. Is this correct? I'm having the same problem on my 800 series.

(quoted from post at 08:32:41 09/16/17)
Keith you say NEGATIVE post. Is this correct? I'm having the same problem on my 800 series.

Click to expand...

larity is important, as Keith speaks of both original 6v positive ground and the fellows 12v negative ground conversion. Which do you have?

Hi Keith, I just wired my tractor and I have a question regarding the 4 post solenoid.
I read the long version in the archives and I'm not sure which post is for the starter button and which post is for the orange wire to the terminal block I believe they were called I and S terminals in the long version by john in LA. I cant seem to find markings
thanks
Jon

(quoted from post at 15:50:45 09/19/17) Hi Keith, I just wired my tractor and I have a question regarding the 4 post solenoid.
I read the long version in the archives and I'm not sure which post is for the starter button and which post is for the orange wire to the terminal block I believe they were called I and S terminals in the long version by john in LA. I cant seem to find markings
thanks
Jon

Click to expand...

OESN'T MATTER.....EITHER TERMINAL TO EITHER PLACE.

At some point my 1956 640 was rewired to 12V neg. gnd with the 4-pole solenoid. The big terminals (Load Circuit studs) are to the battery and the starter. The little terminals should be labeled "S" and "I".

S - is wired to the starter button.

I - is wired to the coil. You don't have to do it this way. You can run the coil right off the bus that the key-switch closes if you don't want to use that terminal.

(quoted from post at 11:08:49 09/21/17) At some point my 1956 640 was rewired to 12V neg. gnd with the 4-pole solenoid. The big terminals (Load Circuit studs) are to the battery and the starter. The little terminals should be labeled "S" and "I".

S - is wired to the starter button.

I - is wired to the coil. You don't have to do it this way. You can run the coil right off the bus that the key-switch closes if you don't want to use that terminal.

Click to expand...

All very helpful info
thanks