Starter Wiring, Why doesn't my car look like all the others?!? Options

[Blue Lightning]

1976 2.0. Putting engine back in after a 2056-dectomy, but it has been out too long and as usual I didn't take enough pictures of all the important connections.

There are many threads on wiring for the starter. However, I have one additional wire that I don't see in any of those threads, but I marked as going to the starter solenoid.

Wire in my hand:

Way off to right:

Out of focus in center:



The wire in question is red and has a spade terminal on the end. It is not the cable that runs from the alternator. My best guess as of today is that is leads up to the firewall and goes through here:


Thoughts? Car has air conditioning, so is this part of that?

[chmillman]

How much current does the original solenoid draw actually?

[Superhawk996]

How much current does the original solenoid draw actually?

25A at ambient temperature.

[chmillman]

How much current does the original solenoid draw actually?

25A at ambient temperature.

The solenoid or the starter...??? I can't imagine the solenoid taking 25A...

[Superhawk996]

The solenoid or the starter...??? I can't imagine the solenoid taking 25A...

Solenoid

I’ve measured it with an accurate shunt resistor.

There is a reason the yellow solenoid wire is large (4.0mm^2 area) which is approx an 11 AWG size.

[chmillman]

I’ve measured it with an accurate shunt resistor.

There is a reason the yellow solenoid wire is large (4.0mm^2 area) which is approx an 11 AWG size.

OK, interesting, learned something here. I went and looked at the 914 manual and I see that the 'solenoid' is not only actuating the relay contacts in this case, but also pushing the starter drive shaft to engage the flywheel. Which I guess could explain the large current draw.



And, it actually says it could draw up to 35 amps...



This instead of the typical inertial Bendix mechanism that is used for example on my '57 Ford T-Bird - there the 'solenoid' just is a relay to switch the starter motor current. It's actually the exact same one you're proposing to mount on the 914 - the design hasn't changed from the '50's... I looked and it draws 'only' 8-10 amps. That's still a fair current draw for a relay, but it's electromechanical (not solid state) and according to my T-Bird manual designed to switch up to 500 amps.

So, if I understood correctly, you're using this Ford solenoid as a relay to switch current to the 914 'solenoid' - as that still needs to function in order to engage the drive gear - you're not bypassing it altogether. So you're switching ~25-35A with a solenoid built to handle 500... and which still draws 8-10A. Not better to use a solid-state diode-protected 50A relay - which draws a fraction of an amp instead?