Starter solenoid

[Dragsinger]

Eman has a good thought in ref to factory wire size. A SWAG could be ascertained in that Ford has an 18 gauge wire to bring in the solenoid whereas GM employes a 12 gauge wire.

[FireSale]

i have one of those red MSD starters that probably came off a 747 based on the torque it provides. It doesn't require a Ford style relay/solenoid and has a wiring diagram that allows a 12 gauge wire to basically be connected directly to a start switch. Only problem was that this provided for the big wire on the starter to be connected directly to the battery at all times when the car was on. My steering shorted it out making a hard turn to get to the staging lanes. Burned out a 150 amp cutoff switch. I wound up wiring in a Ford solenoid to manage the battery power during start. My current headers won't clear the starter and I don't miss the drama.


On a side note, I have found that continuous duty Ford style solenoids make very good relays. They cost more but are very reliable.


Another trick: If you use a Ford style solenoid fender mounted to send power to the starter, there is a reverse voltage surge that travels on the small wire back to the starter button when the switch is released. This is caused by the collapse of the magnetic field in the solenoid and can damage the starter switch or wire to it. I replaced a push button with thin gauge wire with a beefy momentary toggle switch and 14 G wire because of this. You can also wire a diode in that small wire to block reverse current if you understand those things.

[Eman]

Originally Posted by FireSale

Another trick: If you use a Ford style solenoid fender mounted to send power to the starter, there is a reverse voltage surge that travels on the small wire back to the starter button when the switch is released. This is caused by the collapse of the magnetic field in the solenoid and can damage the starter switch or wire to it. I replaced a push button with thin gauge wire with a beefy momentary toggle switch and 14 G wire because of this. You can also wire a diode in that small wire to block reverse current if you understand those things.

This is a good point, I've had it happen but not with every GM starter when you use a Ford solenoid.
Another thing you can do is use a Ford style solenoid and use it as a relay to trigger the 12ga wire to the GM solenoid on the starter. You should use a relay on a GM starter switch circuit if you use a micro switch for a neutral safety switch.

[Painter]

You guys are making this way to hard. Simply put a jumper wire between the battery post on the starter and the start terminal. Now when the “slave solinoid” is triggered it sends voltage to both terminals! Wow! How simple can you get. No small wire even going to the starter to get burned by the headers. Battery cable going to the starter is only hot when you try to start. Takes very little amperage to trip slave, and the solinoid on the starter is trip by battery voltage and amerage. Win-win situation.

[Rich Biebel]

And use a Cole-Hersee HD all metal continuous duty rated slave solinoid. The plastic ones can and will stick and your starter stays engaged. None of these solinoid are as well made as they once were. I cut open a few and an old Ford style laying in my toolbox for probably 30-40 years was all copper inside. New ones use cheaper materials. It’s a very good way to keep long run battery cables from being energized all the time. Much safer ....

[Eman]

Originally Posted by Painter

You guys are making this way to hard. Simply put a jumper wire between the battery post on the starter and the start terminal. Now when the “slave solinoid” is triggered it sends voltage to both terminals! Wow! How simple can you get. No small wire even going to the starter to get burned by the headers. Battery cable going to the starter is only hot when you try to start. Takes very little amperage to trip slave, and the solinoid on the starter is trip by battery voltage and amerage. Win-win situation.

That's exactly what Firesale posted, but he also warned at how doing this can cause the starter to stay engaged at times.

[FireSale]

Originally Posted by Eman

That's exactly what Firesale posted, but he also warned at how doing this can cause the starter to stay engaged at times.

Kind of. The starter positive post was always hot and shorted against my steering. Here is the simple wiring diagram from an MSD Dynaforce starter. The one I ran the starter positive through a Ford solenoid. A little too simple.

[FireSale]

Originally Posted by Painter

You guys are making this way to hard. Simply put a jumper wire between the battery post on the starter and the start terminal. Now when the “slave solinoid” is triggered it sends voltage to both terminals! Wow! How simple can you get. No small wire even going to the starter to get burned by the headers. Battery cable going to the starter is only hot when you try to start. Takes very little amperage to trip slave, and the solinoid on the starter is trip by battery voltage and amerage. Win-win situation.

I have friends at the track who rebuild starters and alternators for a living and they say this shortcut will shorten the life of the starter. When you hit the switch with a jumper in the mix you send the 12 volt signal from the battery that is intended to spin the starter (up to 1000 amps) to the starter solenoid as well. That only requires 12 volts 5 to10 amps to engage the gearing and energize the motor. It will burn out the windings in the solenoid. It's just an electromagnet and a pushrod. A starter mounted solenoid has studs of different sizes for a reason. Wire it like the manufacturer intended and it will last longer.