trying to wire my model A. i have a flathead w/alt and as a source i'm using "how to wire you streetrod from start to finish by jack sweeden. the book shows 3 types of gm alternators. one is used with an external regulator. the other two look like my and they apparently don't use a voltage reg but they both have two terminals in the top. one, the book calls a "one wire alt", doesn't use the two top terminals. the other does 1 for the horn relay and the other to the ignition switch. how do i know which one i have.
The one wire jobs usually have a cover over the plug and just use the big wire. You could take it to a alternator shop or parts house and have it tested
The plug in the top is different. Internal has a flat terminal about a 1/4 x 1 inch. The spade terminal are longways side by side. The external has a square plug. About 1/2x1/2. The spade terminals face each other. Hope tis might help. Do a,search and you will find a wire diagrham here. Use the internal regulated. Easier.
The other two alternators you have contain internal voltage regulators and will most likely be either 10SI or 12SI models. Depending on who you ask you will get a mul***ude of answerws as to whether one iwrea alternators or three wire alternators are better. Both work and each has its good points. The one wire model is easy to connect and has a self exciting circuit but doesn't start charging until about 1100 RPM. Once "excited" it will continue to work until the vehicle engine is shut off. The three wire model has two lighter gauge wires (usually red and white), the red wire can be connected to the terminal thta the heavy gauge wire connects to and the white wire goes to a lamp on your dash via a switched connection. This wire supplies the initial cuurent to the alternator to start it charging and the lamp acts as an indicator for charging. The lamp goes off when the alternator is charging and lights up when the alternator stops charging.
This diagram goes along with the info that CB Chief posted in the second paragraph of post #5 This shows the alternator either 10 si or 12 si that he described that has the "internal" voltage regulator and how the majority of us hook it up putting a diode in the exciter wire but the light shown in the other diagram works just as well.
That works well when you have an Accessory side on the switch. Some of the rigs we have are pre accessory or have a switch that doesn't have an accessory side. The one with the photo of the alternator (second Photo) was actually borrowed from a farm tractor forum. As long as it doesn't feed back to the ignition when you shut the key off you are good to go. To add to that I saw one wire alternators for Farm equipment applications before I saw them advertised for hot rod applications. Primarily because many of them have mag ignition rather than battery ignition and for diesel applications.
I have a 1939 chevy master deluxe 1997 350 motor alternator has 3 wires from plug in where do they go i hadf alternator checked it is good but still not charging. I have wire to battery from alt. but stuck on other wires
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