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starter sol with 3 connections vs. 2

starter sol with 3 connections vs. 2

Old September 20th, 2009, 07:53 PM
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starter sol with 3 connections vs. 2

My 68 cutlass had an inline 6 cylinder. The starter solenoid had one large connection and two small. I'm adapting the original wiring harness to fit a '71 455. I happen to have a good '76 starter for a 455 but I see it only has two connections on the solenoid (one large and one small). Although I don't have the original anymore, it had 3 connections at the solenoid (one large and two small). Do I need to get an earlier starter, or, do I modify the way it is wired?
The two wires in question are:
purple wire from old solenoid went to neutral safety sw. then to ignition
yellow wire from old solenoid went to positive side of coil
Thanks.
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Old September 20th, 2009, 08:00 PM
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That 3rd contact was usually to give full battery power to the coil during cranking.
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Old September 20th, 2009, 08:15 PM
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Required? or just nice to have.
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Old September 20th, 2009, 08:28 PM
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depends on the car.
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Old September 21st, 2009, 01:29 PM
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The 3rd post helps start especially in cold weather. If it is a warm weather car you may not need it, but I would advise you either swap solenoids or get a solenoid with the 2 small posts. Another thing you could do is run the yellow wire to the other big post on the solenoid, (the one where the starter field leads connect to the solenoid) but you would then need to put a diode in the line to prevent feeding the starter fields when the car is running. The easiest and safest as well as best thing to do is get a solenoid with the 2 small posts. If you have a local starter rebuilder close, he can add the 2nd small post for you.
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Old September 21st, 2009, 01:43 PM
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Originally Posted by stellar View Post
The 3rd post helps start especially in cold weather.
The two small posts on the Delco solenoid are the "S" terminal, which is the start terminal, and the "R" terminal, which is the resistor wire bypass terminal. On point-style distributors, a resistor or (in the case of most GMs) a resistor wire is used in the RUN position to reduce the voltage to the points for increased life. Starting is enhanced by bypassing this resistance while cranking. Olds did this in one of two ways, either with a wire from the "R" terminal on the starter to the coil or with a bypass wire directly in the harness. ALL cars with points had the bypass. If your wiring is set up to use both terminals on the starter solenoid then changing the solenoid is a good idea. Changing the solenoid is trivially easy when the starter is out of the car. Simply remove the bolt that connects the solenoid lower terminal to the starter windings, remove the two small screws that hold the solenoid to the starter nose, and loosen (but do not remove) the two bolts that go all the way through the starter from front to back. Now rotate the solenoid (in either direction) until the tab on the solenoid clears the starter housing. Reverse the procedure (remembering the spring in the solenoid) to reinstall.

Of course, if you are converting to HEI then you need to bypass the resistor wire anyway and this whole discussion becomes moot.
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Old September 30th, 2009, 07:45 PM
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According to Robbmc performance, the R terminal is only required with stock point style ignitions. If you are running HEI or a Petronix, it is not necessary.

I found this out when I unsuccessfully tried to fit-up my existing starter between the header and oil pan. No-go. I splurged for the widely acclaimed Robbmc mini starter to get the job done when the tech guy told me it would be OK with 2 terminals on the solenoid (although they offered to add the other for $10 more). I was impressed when they told me either way they would build it for me and ship it next day.
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Old October 16th, 2010, 07:37 PM
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Searchable key words: Solenoid wires, solenoid diagram , Starter wires, Starter diagram, Coil wires, coil diagram.

Note : Finding the resistance wire. The resistance wire is a wire that is made of silver strand wire. The actual alloy creates a voltage drop form 12V to 9V. You will not see the 9V when chacking with a volt meter. It will appear as 12V.
If you get connect a spare headlight to the battery pos and neg, it will glow bright.
To identify the resistance wire use it as a positive feed to the spare headlight.
You should notice the light is dim compared to when it was connected directly to the battery +.
Chrysler cars had a ceramic resister that mounts on the fire wall.
They are usually not hard to find. Be careful, they get hot and can burn you and can also burn out.
Resistance wires never go bad.
If you need a new end on the resistance wire crimp one on. Soldering is very difficult.


Last edited by Homestar; October 16th, 2010 at 07:52 PM.
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Old October 16th, 2010, 07:43 PM
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