Alternator wire?

Ok so on the car I’m working on now is a somewhat basket case. 71 gs 350 auto. Looks like the alternator wiring is a disaster. Looks like the wires and voltage have been cut and removed. Appears that a newer style alt is installed with an internal regulator just has one wire running of the lug going straight to the battery. What’s anyone’s opinion on this. I know what needs to be done but it’s been this way for a long time so I guess it works.

 

One wire alternators are a popular swap. If it works I would leave it. Maybe tidy up the wiring?
Does the alt light work?

 

Thanks. Very good info

 

Larry - that's for the 10/12 si 3 wire. It sounds like he has a 1 wire. This might help: http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

 

Someone did that to my 72 and I could not stand all the cobbed wiring, so I installed a new harness.

 

The stock wiring setup is actually a bit messy and more complex due to the external regulator. Also the stock wiring setup cannot safely be used with a higher output alternator as the main output wire is just 10AWG. This wire also happens to be inside a heat insulating wiring harness and close to the warm engine. An internal regulator can eliminate 3 cables or so which makes for simpler wiring and fewer potential points of failure.

Connecting the alternator directly to the battery makes for a clean wiring topology that is easier to follow and troubleshoot in my opinion. However, it is recommended (and actually required by US regulations I think) that you protect the alternator cable with a fuse. It is best to put the fuse close to the battery. In case e.g. the wire insulation breaks the battery will not be directly shorted. From the alternator side, it is enough that you use a wire sturdy enough that it will allow the max rated output current of the alternator. Some alternator manufacturers have recommendations on what wire gauge you need, see e.g.:
http://www.powermastermotorsports.com/alt1_gm_si.pdf

Here are some notes on how I choose to rebuild my engine wire harness:
https://www.v8buick.com/index.php?threads/fusible-link-what-to-do.383521/

 

Huh - interesting!

 

That may work - but according to Mad Electric: the 3 wire alternator: "The other of the two plug-in wires at the SI series alternator is the “voltage-sensing” terminal for the voltage regulator. Through the sensing-wire, the voltage regulator monitors electrical system voltage and makes adjustments to alternator output. "
On the 1 wire:"After the engine has been started, and the alternator is spinning, the existing weak magnetic field from the iron core material will cause the alternator to produce a small amount of current. This small amount of current is used to turn the voltage regulator electronics ON (rather than wiring a special wiring circuit to turn the voltage regulator ON). " The 1 wire has to have an internal voltage sensing circuit, which the 3 wire doesn't have. Now, some aftermarket (Powermaster for one) units can be used either way as they are made with both sensing circuits.

Full text: http://www.madelectrical.com/electricaltech/onewire-threewire2.shtml

 

btw Note 1970- what alternator do you have?

 

This is easy and not cut up all your wiring. Why mess with anything else....





[paste:font size="4"]Alternator Conversion Harness Kits

Alternator Conversion Harness
Part #VAK6368SI
(click to enlarge)
Now you can upgrade your alternator/generator and not have to cut or splice into your original wiring harness!

This simple plug-in conversion kit allows the use of a Delco-Remy 10SI or 12SI internally regulated alternator in place of the original "DN" (or Delcotron) series, externally regulated alternator. "SI" series alternators were commonly used on 1975-85 G.M. vehicles (or 1969-86 Corvettes). Two ways to help identify a 10SI or 12SI alternator is the V-belt pulley and 2 horizontal male-blade terminal connector (terminals typically labeled 1 & 2) present on the backside of the alternator. Note that the alternator case and pulley-type can vary among models of alternators.

In addition to including the alternator adapter, this kit also includes the 4-terminal voltage regulator bypass module to eliminate your external voltage regulator. This bypass module simply plugs into your wiring harness, where your voltage regulator was previously connected.

Alternator Conversion Harness Kits are available for several year/make/model cars. PRICE and BUY for your specific vehicle.