Inliners International Forums General Discussion Electrical alternator wiring

i have installed a motor with an alternator . where do the wires go . i am starting the full wiring of the truck from scratch .this is a mid 60's chevy 6-250 and it has the smaller 2 wire plug .i think there is also a post on the outside of the alternator for a connection. i checked my newer truck and the post is constant hot and so is one of the two wires on the plug . the second wire becomes hot when the ignition is turned on . i just don't know where these go on the other end . anybody?

It depends if your alternator has the built in regulator or not..Usually remote type have the two wire plug on the end while built in have the two wire plug more or less on the side.The remote plug is usually pretty square and the built in ones are more rectangular..BUT!!..that is not always the case..I have both type Delco alternators..I just wrote a book on how to tell the difference but erased it all because it would probably just confuse you..So...take your alternator to your favorite part store that can test alternators and they can tell by doing a output load test...The built in regulator type is best and easiest to wire..I get Delco alternators from the parts yards but always look for non rebuilt ones..The rebuilders use cheap offshore parts and or used..I have seen some with used brushes and regulators..With the non rebuilt you are at least getting GM parts that are pretty good...You can make a GM Delco with built in regulator work on just about anything..I have built mounting brackets and mounted them in many a Ford --forklifts of all kinds---endless farm tractors---different machinery and of course Chevys..There is no end to the pulley selection that will interchange from all years...

I read your post a little slower a second time..The wire you have that is hot when the ignition is on would be the "switched" wire. It will go to the terminal marked #2 on the alternator..This is exciting the field to activate a charge..The large red wire is hot all the time..The other small wire operates the dash charge indicator light..If you want to monitor the system from the drivers seat a voltmeter can be connected to the "switched" wire providing it has a full 12 volts when the ignition is on..Do be sure if you have a built in regulator or not..

It depends if your alternator has the built in regulator or not..Usually remote type have the two wire plug on the end while built in have the two wire plug more or less on the side.The remote plug is usually pretty square and the built in ones are more rectangular..BUT!!..that is not always the case..I have both type Delco alternators..I just wrote a book on how to tell the difference but erased it all because it would probably just confuse you..So...take your alternator to your favorite part store that can test alternators and they can tell by doing a output load test...The built in regulator type is best and easiest to wire..I get Delco alternators from the parts yards but always look for non rebuilt ones..The rebuilders use cheap offshore parts and or used..I have seen some with used brushes and regulators..With the non rebuilt you are at least getting GM parts that are pretty good...You can make a GM Delco with built in regulator work on just about anything..I have built mounting brackets and mounted them in many a Ford --forklifts of all kinds---endless farm tractors---different machinery and of course Chevys..There is no end to the pulley selection that will interchange from all years...

here is an update on my wiring for the altenator . i figured out i needed the regulator by the style . i went to the junk (to some!)yard and found the regulator and all the wiring between the two . i couldn't tell where the wires that left this whole mess into the firewall went but there were three . one large hot ,one smaller hot and a maybe20 guage off color . i am thinking this was for the idiot light . where should i put the smaller hot wire .i think i have it to the switched ignition side .i may have it right but wanted a second opinion .i have a voltmeter and can't really tell yet if it is charging . no accesories to speak of hooked up yet.

If you think you have it hooked up right but dont know if it is charging, then do what I did.Start your truck, then while its running unhook the battery.If it stays running then the alternator is charging.If it dies then its not charging or your wiring still isnt right.

Ground the black lead of the volt meter to ground and touch the red lead to the 10/32 battery stud on the back of the altenator.
Then the output of the alt should be read on the volt meter. At fast idle output is around 13.5 to 14 volts.
Do the same procedure to the battery posts. The difference between the two should be less than half a volt. If its more then you have high resistance in the charging circuit probably caused by dirty or loose and corroded connections.

If your just interested in seeing if its charging touch the smooth bearing surface on the back of the altenator housing with a screwdriver while the engine is running. If its charging, the bearing surface will be magnetized. If you can't tell, turn on the headlights and heater blower motor and it will increase the load and magnetism.

1970's and newer altenators were built with internal regulators. If yours is external, it is from the 60's. The GM 10SI series altenator from 1973-85 is thought to be the best for upgrading earlier generators or altenators. Simple 2 wire hookup and 60 amp output. They have the exciter wire. Your pulley should be 2.5" diameter. Anything bigger will reduce your output at idle and low rpm.

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Stuck in the 50's
1951 Ply Concord truck
1954 Nash Rambler 2 dr
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Hello, I am e-mailing you some diagrams and charts that might help out---Paul

you guys are awesome . been wrenching for most of my life .good to learn new tricks .

Paul,
Could you send the diagrams to me as well?

Thanks,

Bob Dale

Hello Bob, they are on the way--sorry I didn't see your post sooner-- maybe they will help---Paul