I get why a hot rod might use the Ford solenoid so as to take advantage of the battery studs for things like the 1-wire alt. or hooking up power feeds.
I get that you are disconnecting the battery cable to the GM solenoid. I get that you are now attaching a battery cable from the Ford solenoid right back where you just took off the GM cable.
I get that you are removing the Purple "Start" wire to the "S" terminal post on the GM solenoid and are now running a jumper wire from the battery cable lug on the solenoid to the "S" terminal.
I get that you connect the battery cable from the positive battery terminal to one side of the Ford solenoid's battery lug, the other battery lug has the cable that runs to the GM starter solenoid lug along with the jumper S "Start" wire.
I get that there is no power going to the GM starter using the Ford solenoid as a 12V power cut off switch, and with the old GM set-up the battery/12V is constant to the solenoid.
I get it that the Purple "Start" wire that went to the GM "S" solenoid post now gets attached to the smaller "I" post on the Ford solenoid and when you turn the key to "Start" that this opens the flow of electricity between the battery post-to-solenoid lug and to the opposite solenoid lug-to-GM solenoid battery post. I get that by doing this change over in location of the Purple "S" from the GM solenoid to the remote Ford solenoid removes it from being near the heat of an exhaust manifold or header.
Here is what is listed on the MAD description, "The problem occurs because the large solenoid on the GM starter draws 40 to 50 amps at the moment the key is turned to "START." And that large amount of current must flow through a very lengthy circuit, from the battery to the dash area. Through dash wiring and switches, back out through the under-hood wiring, finally to the starter."
OK, the activation of either the GM solenoid or Ford solenoid is still being activated by the Purple "Start" wire, all I did was move it from the GM solenoid "S" lug to the Ford solenoid "I" "Start" lug. HOW DID I CHANGE/ELIMINATE the current flow through a very lengthy circuit from Ford solenoid lug to the dash area, through dash wiring and switches, back out through the under-hood wiring, and finally to the Ford solenoid "I" lug??????
Enclosed is a drawing that is my example for the above. I still have to connect the 12V power wire that was attached to the GM solenoid that brings power to my circuitry/fuse box. So the current flow HAS NOT changed going through the lengthy wiring circuit because it still has to in order for it to energize my ignition switch that sends power out along the Purple "Start" wire to activate the Ford solenoid through the "I" lug. So all I am doing is swapping my GM solenoid 12V power wire that supplies 12V to all my switches/gauges/accessories to the 12V battery lug on the Ford solenoid having the battery cable going from the battery post to the Ford solenoid lug - I will still have constant 12V going into my wiring circuitry, just not to the starter. AND, depending where I mount the Ford solenoid, I may have to extend/splice the 12V power wire/Purple "S" wire to reach the remote Ford solenoid.
MAD also says, "
(2) SLOW CRANKING, a gr-r-runt, gr-r-runt. This kit (Ford solenoid) won't fix it! You'll need to work with ignition timing, battery cables, the starter, and the rest of the system."
Another website compares the GM set-up with the Ford change over and states, "This set-up DOES NOT make the GM solenoid any cooler. It just gives it a better current supply." Well, better current supply may also depend on battery condition, cable length & gauge size, good connections, good grounds, and any corrosion or frayed wiring that can lead to resistance.
I get why a hot rod might use the Ford solenoid so as to take advantage of the battery studs for things like the 1-wire alt. or hooking up power feeds.
I get that you are disconnecting the battery cable to the GM solenoid. I get that you are now attaching a battery cable from the Ford solenoid right back where you just took off the GM cable.
I get that you are removing the Purple "Start" wire to the S terminal on the solenoid and are now running a jumper wire from the battery cable lug on the solenoid to the S terminal.
I get that you connect the battery cable from the battery to one side of the Ford solenoid's battery lug, the other battery lug has the cable that runs to the GM starter solenoid lug with the jumper S "Start" wire.
I get that there is no power going to the GM starter using the Ford solenoid as a interpreter/cut off switch, and with the old GM set-up the battery/12V is constant to the solenoid.
I get it that the Purple "Start" wire that went to the GM solenoid now gets attached to one of the smaller lugs on the Ford solenoid to create the connection between the battery post -to-solenoid lug and solenoid lug-to-GM solenoid battery post, and that it is removed from being near an exhaust manifold or header.
Here is what is listed on the MAD description, "The problem occurs because the large solenoid on the GM starter draws 40 to 50 amps at the moment the key is turned to "START." And that large amount of current must flow through a very lengthy circuit, from the battery to the dash area. Through dash wiring and switches, back out through the under-hood wiring, finally to the starter."
OK, the activation of either the GM solenoid or Ford solenoid is still being activated by the Purple "Start" wire, all I did was move it from the GM solenoid "S" lug to the Ford solenoid "I" "Start" lug. HOW DID I CHANGE/ELIMINATE the current flow through a very lengthy circuit from Ford solenoid lug to the dash area, through dash wiring and switches, back out through the under-hood wiring, and finally to the Ford solenoid "I" lug??????
Enclosed is a drawing that is my example for the above. I still have to connect the 12V power wire that was attached to the GM solenoid that brings power to my circuitry/fuse box. So the current flow HAS NOT changed going through the lengthy wiring circuit because it still has to in order for it to energize my ignition switch that sends power out along the Purple "Start" wire to activate the Ford solenoid through the "I" lug. So all I am doing is swapping my 12V power wire that supplies 12V to all my switches/gauges/accessories to the 12V battery lug on the Ford solenoid having the battery cable going from the battery post to the Ford solenoid lug - I will still have constant 12V going into my wiring circuitry, just not to the starter. AND, depending where I mount the Ford solenoid, I may have to extend/splice the 12V power wire/Purple "S" wire to reach the Ford solenoid.
MAD also sayd, "
(2) SLOW CRANKING, a gr-r-runt, gr-r-runt. This kit (Ford solenoid) won't fix it! You'll need to work with ignition timing, battery cables, the starter, and the rest of the system."
Another website compares the GM set-up with the Ford change over and states, "This set-up DOES NOT make the GM solenoid any cooler. It just gives it a better current supply."
Heat shields for the starter/solenoid, heat wrap, and heat blankets can help keep heat away.
Using a heavy gauge battery cable can improve the voltage supply to the starter.
From a other post, "One area that people forget is the "ground" path. If you are supplying 150A from the battery to the starter motor, then 150A has to go back from the starter motor to the battery. There are two current paths to deal with, not one. Remember that strap from the cylinder head to the firewall that you didn't bother to put back on because it was a pain? Put it on. Run the same sized cable from the starter to the chassis as you do from the battery to the solenoid, then make sure that the negative side connection from the battery to the chassis is excellent, nothing less."
From another forum with regards to needed amps to spin a 2HP GM starter, and I am going to guess this is with no load on it, ie spinning freely, "At 746 watts/hp, a 100% efficient 2 hp starter would draw about 125 amps at 12v. If the starter is only 75% efficient, it would take 166 amps to get the same 2 hp. If the applied voltage drops to 10 volts because of the load of our 75% efficient starter, it will now take 199 amps to make 2 hp."
A good
starter will normally
draw 60 to 150
amps with no load on it, and up to 250
amps under load (while cranking the engine). Amp needs can go even higher depending on your compression, timing, oil weight and outside temperature. And if brushes, armature, bushings are worn out in the starter itself, efficiency drops and more amps may be required
So
my personal opinion is that I really don't see many advantages to use the Ford solenoid and I would not use one on my car. It may be more of a band-aid than a fix when the heat-soak problem may be cured with correct/larger gauge cables, heat shielding, good battery, or mini-starter with clockable solenoid. I can see an advantage to connecting a 1-wire alternator wire to the solenoid lug being a cleaner installation than most who hook it to the battery post. The positive cable lug on the Ford solenoid would be a good place to hook up any accessory wires such as electric fans, relays, or electrical add-ons. Eliminating constant power to the starter? To what gain?