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How does a starter solenoid work?

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03-15-2005, 02:59 PM
timnlana
How does a starter solenoid work?
Question one; is there a remote solenoid available for the Chevrolet starter motor? This is a gee whiz question just something I have been thinking about prompted by the questions we have raised about heat damage to the starter solenoid.

Question two; there are three wires that go to my starter solenoid, The power from the battery (00 battery wire), power from the starter switch (a 12 gage wire that goes though a transmission cut out switch) and one more wire I do not understand. The wire I do not understand is a 14 gage white wire, I think it provides 12 volts but I do not understand its function.

Oh yes headers, Bill H is correct the Thorney Headers are a good fit on my big block. Easy work with that rust stuff Bill talks about. Note, running a 454 with just headers will cause a number of people from every house in about a quarter mile radius to come over to see what you are doing.

The wiring questions have come up because each time someone added something to the coach and remember this is a 1973; they pulled a new wire. While I have been doing the headers, I have been rationalizing the wiring. The wiring harness had chafed and shorted to the block in several places and… Well you get the idea, it is time for some reflective work.




[This message has been edited by timnlana (edited March 15, 2005).]
03-15-2005, 07:06 PM
Gunner
"Question one; is there a remote solenoid available for the Chevrolet starter motor?"

MY understanding: The starter solenoid, when energized, mechanically moves the starter motor gear "forward" (actually towards the rear of the vehicle) into contact with the flywheel and begins the rotation of said starter gear, cranking the engine; when the engine starts and/or the key is released the starter motor stops rotating and the starter gear retracts from the flywheel.
Because the starter gear must make contact with the flywheel, it must be physically located immediately next to it. The "ideal" place on Chevys is the passenger side lower rear engine quadrant; unfortunately, this is behind/beneath the cast iron exhaust manifold next to the exhaust pipe. One of the many advantages of aftermarket headers is they are not cast iron (a heat sink) and are significantly cooler; sometimes they are further away from the starter.
PS: Is "Thorney Headers" a misspelling?? Thirty years ago I had Doug Thorley Headers on some street racers and they were wonderful: state-of-the-art at the time.
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"You are what you drive" - Clint Eastwood



[This message has been edited by Gunner (edited March 15, 2005).]
03-15-2005, 08:01 PM
timnlana
Thorley is the correct spelling, thanks for seeing that.

They are still a well made product.

The white wire is what I don't get. The wire from the starter, ok energize magnet to close switch, big fat wire power to motor, that is easy to see but the third white wire I for the life of me just don't quite get.
03-15-2005, 10:22 PM
Grizzlygiant
quote:
Originally posted by timnlana:
Question one; is there a remote solenoid available for the Chevrolet starter motor? This is a gee whiz question just something I have been thinking about prompted by the questions we have raised about heat damage to the starter solenoid.

Question two; there are three wires that go to my starter solenoid, The power from the battery (00 battery wire), power from the starter switch (a 12 gage wire that goes though a transmission cut out switch) and one more wire I do not understand. The wire I do not understand is a 14 gage white wire, I think it provides 12 volts but I do not understand its function.


The post on my starter has a wire to the ignition (white wire???) plus a heavy wire to the isolator plus a heavy wire to the chasis battery. This multiple connection has been a source of trouble due to the post stretching with heat and allowing poor contacts.
03-16-2005, 12:52 AM
Gunner
" but the third white wire I for the life of me just don't quite get"
Shade Tree Solution: disconnect the white wire and see what doesn't work - crude, but often very effective.

------------------
"You are what you drive" - Clint Eastwood
03-16-2005, 05:32 AM
bill h
Tim, if your 454 is pre-HEI, the other small wire is a resistor wire bypass. It's purpose is to provide full voltage to the ignition coil when the battery voltage is pulled down by the starter load.

The ignition coil is really an 8 or 9 volt coil, not 12 volts. When the engine is running, the alternator is putting out 12 volts, but a resistor (or resistor wire) is cutting the voltage down to 8 or 9 volts, its design voltage.

When you crank the engine, the load drops the battery voltage down to 8 or 9 volts. At the same time, a contact is made inside the solenoid cap to provide full battery voltage (8 or 9 volts) to the coil while cranking, bypassing the primary resistor. This gives you full voltage to your coil for a good hot spark. As soon as the engine fires, you release the start switch, and the primary resistor is now supplying the 8 or 9 volt to the coil from the 12-14 volt system.

Didja get the stuff I sent?
03-16-2005, 04:50 PM
timnlana
Bill I have not looked at my personal email in over a week. I'll check now.

Yes my set up is as you describe, the power to the coil is a red wire marked "Resistor wire do not cut" and the output from the starter is spliced into the harness at the end of this wire. Now I understand.

Thank you so much:

Timothy