Customs Jumper wire size

I have a mini starter on my Flathead Merc. Not too sure what gauge wire to use for either a jumper wire from battery post to starter or from remote solenoid down to the starter. Should it be at least 12 gauge wire? And if a smaller sized wire is used could that cause starting problems?

 

If you have a 12 volt system it should be at least a #2 gauge, if 6 volt a #0 or #00. You are talking about the main power feed to the starter, right?

 

Unless you have an on the starter solenoid that you are trying to trigger the Battery cable from the solenoid works better if it is at least a #2 when all is said and done as the thinner the battery cable the more resistance you have for amp flow to the starter.
Think of it as you would a water hose, You can have the same pressure pushing water though a 3/8. 1/2 or 3/4 inch hose but that same pressure will flow a lot more water (=amps) through that 3/4 inch hose than it will through a smaller hose.

 

Need a cable not a jumper wire.

 

Oh, you are using a remote solenoid, the little jumper wire from the batt terminal to the start side of the solenoid on the starter can be 10 guage.

The battery cable, I use 1 guage fine strand pure copper.

 

12 volt system, I’m not talking about the battery cables, I’m talking about the wire from the starter solenoid down to the starter. 12 gauge? Or smaller

 

This is counterintuitive. You say solenoid to starter, that too is to be the size of a battery cable. If it were not so hazardous I'd say try to power that starter with a small wire, but it will burn in mere seconds. Takes a MINIMUM of 100 amps to crank a loaded starter.

Not trying to be a dick, but you need 2 battery cables at the solenoid, 1 side to the battery and the other side to the starter post, and a trigger wire from a switch to the solenoid which can be like a 10ga. Got a picture? The wording has me confused.

 

Thanks

 

A small cable size (for the current it has to carry) will have excessive resistance and cause a significant voltage drop. Less voltage reaching the starter means the starter becoming weaker and slower. A slow starter can absolutely make it harder to get an engine started.

If you exaggerate the problem a way too small cable will get very hot due to being overloaded.

 

If you are using the stock Ford solenoid on the fender or firewall, you need a large gauge cable going from the solenoid to the battery terminal on the starter. You do not need any other wires going to the starter. You just need a jumper wire from the battery terminal on the starter to the S terminal. If you are talking about the jumper wire, 12 or 10 gauge would be sufficient.

 

I had to jack this off the net as I didn't have what I wanted.
If you are using the later Ford Solenoid that works off the start pole on the ignition switch like this one 12 gauge would be the smallest size wire I would consider running from switch to the S pole on the solenoid.
From the battery to the solenoid and from solenoid to the starter the larger battery cable that we suggested rather than what is called "12 volt cable" will save you a lot of grief later for what little extra it costs. Making that change on my OT truck solved hot start problems that I had been fighting since I bought the truck. I had already put a heat shield on the starter and done the Ford Solenoid trick for a Delco starter but it was the bigger diameter cables that solved the problem. That's on a truck that if you park it on enough of a slope to roll when you push the clutch and let off the brake it will fire up when it is rolling at all when you let out the clutch.