Technical Solenoid 8CM

I have a '39 Ford converted to 12v with an 8CM engine. What starter solenoid do I need? I searched and since they all pretty much look the same, 4 terminals- 2 large for battery 2 small one for start one for coil, it is pretty confusing. Especially with limited data available from manufacturers. I'm looking at NAPA ECH ST80.
Any 12v will do?

 

Can't help, but post this on "The Ford Barn"...someone will know. Lots of flathead guys.

 

Yes, however there are some single activator small stud solenoids that have internal grounding and only need power to the one small stud as long as the solenoid is properly grounded.

 

Here one from Amazon that will work:
https://www.amazon.com/Standard-Mot...t=&hvlocphy=9031457&hvtargid=pla-450283045841

 

Be sure you buy the correct one for your vehicle needs.
There are two types out there. One that grounds to activate and another requiring a hot wire.
If the vehicle has a start button with one wire than it would be the grounding type.

 

What Pete said^^^^ are you still using positive ground? or did you convert to negative ground?

 

Neg ground.

 

Pos or neg ground does not matter. What pete said does matter read that post again. I use plain old original ford units with the button on them to activate it from under the hood. 6 volt units work just fine on 12 volts, but they must be mounted so that gravity helps pull the connection off, opposite of the photo above where the coil has to pull the connection up to disconnect. New 12 volt units with the button are available, I believe Cole Hersey makes them, some part numbers on an old thread at the barn

 

You can walk into any legit parts house with the
Standard SS581T number and they can cross it if they don't already carry Standard Ignition products.

 

I have an 8CM in my 40 Ford that has been converted to 12V. My solenoid looks like this: I also use a separate starter button hidden under the dash to start the car. The OEM dash starter button is not connected. I bought the solenoid on Ebay in 2013 for $11. Part # is SS581T. Still works fine. Here it is:
https://www.ebay.com/itm/3843890857...5&toolid=10001&customid=kuuk506agy0025g100004

 

That's part of the problem there are a lot that look just like that. Apparently the difference is isolated or grounded case. That is grounded case.