bullrun Posted September 12, 2021 Share Posted September 12, 2021 I have a 60 Rambler which had it's generator fail. I decided to upgrade to an alternator and bought a kit from an AMC supplier-kit contains bracket and new belt adjustment bracket etc- which accepts a GM alternator style 7127-80's Camaro style internally regulated- no more external regulator. Instructions said run 10g wire from BAT stud on rear of alternator to hot positive cable lug on starter, Then instructs you to run white exciter wire off the plastic plug to the same hot battery lug on starter I hooked up first. Red wire out of plug goes to idiot light feed wire. Hooked up as instructed and start car up and measure 14 Volts at fast idle. All is well I figured. Come back 3 days latter and battery is stone dead. Charge battery up and start up again-check all connections etc and were still charging 14v-OK I figure. Latter that evening I'm reaching over and happen to touch alternator and it's really hot to the touch. I disconnect power and start looking at instructions and figure that the exciter circuit is constantly being fed current- motor running or not with their wiring diagram. I call supplier who puts me in touch with guy that supplies the kits. kit builder says I got an old instruction sheet with bad info and exciter field should not be hot all the time. I now have the exciter wire hot only when car is running. Is that the proper set up or should the exciter wire only be flashed once when the cranking circuit is working? The car sat for a week and today the alternator body was hot and car didn't crank over as fast as it usually does. I suspect maybe one of the may diodes in the alternator may of gone bad and resulted in in a draw or loss-any advice on how the exciter circuit is supposed to be 'fed' for proper use? Just momentarily while cranking or steady while motor is running? thanks in advance. Guy who makes the kits told me a diode may of gone bad the way his instructions showed hook up. Link to comment Share on other sites More sharing options...
m-mman Posted September 12, 2021 Share Posted September 12, 2021 1 hour ago, bullrun said: kit builder says I got an old instruction sheet with bad info and exciter field should not be hot all the time. WOW! send out a "kit" with incorrect instructions(!??) . . . . . That is sad. . . . . Also an example of when an upgrade isnt always an upgrade. Someone will likely be along shortly and assist you in troubleshooting what you are currently working with. Link to comment Share on other sites More sharing options...
joe_padavano Posted September 12, 2021 Share Posted September 12, 2021 The 12SI conversion has been done about a bazillion times. The heavy gauge wire from the threaded BATT terminal goes to your junction block (horn relay stud on GMs, but the starter stud works also, it's just more difficult to reach). The #2 terminal on the alternator is the voltage sensing terminal. It should be run as close to the load as possible, which is why in factory installations it also runs to that junction block stud. The lazy way to wire this is to just run the #2 terminal to the BATT terminal on the alternator. This works, but the regulator won't get an accurate reading of voltage drop in the wiring. The #1 terminal is the exiter terminal and must be run to a switched 12V source with a resistance in the wire. In the factory installation, this terminal runs to the GEN light, and the resistance of the bulb filament is sufficient to turn on the regulator. In cars that use a voltmeter instead of an idiot light, there is a 35 ohm resistor instead. In some later factory installations, the wiring used a resistor in parallel with the lamp (as shown here) so that the alternator continues to charge even if the bulb is burned out. Link to comment Share on other sites More sharing options...
bullrun Posted September 12, 2021 Author Share Posted September 12, 2021 Joe-thanks for your help/ I rewired the unit accordingly after speaking with the guy who offers the kits and acknowledged the directions were in error. Could wiring the the exciter wire directly to a to source-as shown in bad installation sheet-caused the battery to have gone stone dead over several days and messed up one of the diodes which is now causing the alternator to be warm Link to comment Share on other sites More sharing options...
joe_padavano Posted September 12, 2021 Share Posted September 12, 2021 1 hour ago, bullrun said: Joe-thanks for your help/ I rewired the unit accordingly after speaking with the guy who offers the kits and acknowledged the directions were in error. Could wiring the the exciter wire directly to a to source-as shown in bad installation sheet-caused the battery to have gone stone dead over several days and messed up one of the diodes which is now causing the alternator to be warm Wiring the #1 terminal directly to power without the resistor or lamp in the circuit could damage the electronic voltage regulator. Link to comment Share on other sites More sharing options...
trini Posted September 13, 2021 Share Posted September 13, 2021 Should not suppliers double check before shipping items ? It is easy to "sorry". Cannot find good help today. Link to comment Share on other sites More sharing options...
trini Posted September 13, 2021 Share Posted September 13, 2021 bullrun, I have seen some Deco alternators wired with hot wire directly feeding the "F" terminal from the 'BAT". The internal voltage regulator takes care of the rest. To test most alternators if it is working , turn the ignition on and put the blade of a screw driver on the bearing. There should be a fairly strong magnetic pull. In Delco alternators there is a small hole near the bearing, Insert a naked wire into hole , press hard in and ground at the same time on the body { with the engine running }. What you are doing is bypassing the regulator. The voltage can shoot up to 18 volts. The alternator should charge. If not it needs brushes. 12 SI is not much different from 10 si. A hot 'body' is an indication current is feeding the coil un impeded, most likely blown diode/diodes. It is a good practice to open the bonnet once in a while and feel the alternator body. Link to comment Share on other sites More sharing options...
Oldtech Posted September 13, 2021 Share Posted September 13, 2021 If the alternator is that warm I would be suspicious of a diode. If the regulator warmed it that much the regulator should be fried. Link to comment Share on other sites More sharing options...
trini Posted September 13, 2021 Share Posted September 13, 2021 Not really Oldtech, regardless of the configeration of the field, whether it is DELTA or Y it is really a 3 phase AC "motor"and at each end of the wiring the diodes stops there. When the diodes deteriorate it allow the current to flow in the direction it not suppose to The field will be fried You are correct to say a diode is the culprit. Link to comment Share on other sites More sharing options...
Frank DuVal Posted September 14, 2021 Share Posted September 14, 2021 Clarification. The field is not three phase, the stator is. The field is fed 12 volts DC (varied by the voltage regulator) to make the magnetic field. The field rotates (why only two brushes) and the stator is stationary, from whence it got its name, otherwise it would be called an armature.😉 Yes, there are "one wire" Delco alternators, where there is only one wire from the alternator to the battery. It comes on, regulates just fine with no other connection. There is a "special" regulator to do that, although I've seen it done with the normal regulator. This "special " regulator has a jumper between the two terminals you can see. And this connection is wired to the battery + all the time. http://corvaircenter.com/phorum/read.php?1,1127009,1127100#msg-1127100 1 Link to comment Share on other sites More sharing options...
joe_padavano Posted September 14, 2021 Share Posted September 14, 2021 (edited) 10 hours ago, Frank DuVal said: Yes, there are "one wire" Delco alternators, where there is only one wire from the alternator to the battery. It comes on, regulates just fine with no other connection. The problem with one wire alternators is that they were designed for agricultural and industrial applications where the engine operates at a constant RPM. The special one wire regulator typically does not turn on until the RPMs exceed a certain threshold, which is why these units frequently do not charge at idle. It's instructive to note that in an environment where GM tries to shave every penny out of the production costs for new cars, they continued to run the additional wires for a conventional three wire alternator in their production automobiles. What I really find amusing is the people who take a car that already has all three wires in the harness, then use a one wire alternator that costs them more than a normal three wire unit. Even more amusing is the aftermarket companies who convince you that you must use a one wire alternator in your conversion, then charge you an additional $30 for a low voltage sensor module that replaces the idiot light function that came for free with the stock three wire unit. Of course, I have no qualms about making money off of other people's stupidity. https://www.ronfrancis.com/product/98 Edited September 14, 2021 by joe_padavano (see edit history) 1 1 Link to comment Share on other sites More sharing options...
trini Posted September 14, 2021 Share Posted September 14, 2021 There is no doubt that a 3 wire system Delco alternator is simple and easy to repair and service, If installed in a 1929 DB for example., the idiot light can be eliminated . The ampmeter can be wired and a volt meter added. The problem is to find a 6 volt alternator. Compared to a D C Dynamo the Alternator is king in respect to charging . It also takes a few horses off the engine. It needs no external regulator. If I remember correctly alternator has a limitation to charging on low speeds. Dynamo has very little if ever. The point I am trying to make here these old engines runs at top speed of 2800 RPM.. That is ideal for dynamo , not ideal for alternators. Idle speed on my 28 DB 226 is 450-500 rpm. Idle speed on my 72 MGB is 900 rpm. So I will keep this Generator on my DB. I MUST ADMIT MY NAME IS NOT "NOAH OF ALL" so please feel free to correct me. I am 85 years young and have been a mechanic since the age of 16 and I am still learning. Cheers. Link to comment Share on other sites More sharing options...
joe_padavano Posted September 14, 2021 Share Posted September 14, 2021 2 hours ago, trini said: The problem is to find a 6 volt alternator. Actually, six volt versions of the Delco 10SI/12SI alternators are plentiful in the aftermarket. Link to comment Share on other sites More sharing options...
Frank DuVal Posted September 14, 2021 Share Posted September 14, 2021 5 hours ago, joe_padavano said: What I really find amusing is the people who take a car that already has all three wires in the harness, then use a one wire alternator that costs them more than a normal three wire unit. Even more amusing is the aftermarket companies who convince you that you must use a one wire alternator in your conversion, then charge you an additional $30 for a low voltage sensor module that replaces the idiot light function that came for free with the stock three wire unit. Preaching to the choir here! And the idiot light function is absolutely necessary on a Corvair, as it is first line of defense of overheating, from a failed fan belt. Threads on the Corvair forums time and again of how they did it wrong and people try to correct them. The alternator charges better at idle speeds than a dynamo (generator), just watch the ammeter of a typical generator car of the 50s. Early vehicles had the pulley sizes for general slower speeds, so not as big an issue back then. But when top RPM of 5K came around.... had to keep the commutator bars from flying out. Link to comment Share on other sites More sharing options...
trini Posted September 15, 2021 Share Posted September 15, 2021 Just asking. Is the Corvair the GM car with the engine in the trunk ? BORN TO OVERHEAT. Link to comment Share on other sites More sharing options...
Frank DuVal Posted September 15, 2021 Share Posted September 15, 2021 No, engine is in engine compartment behind the rear widow.🤣 It is covered by the engine lid. Only the turbo and A.I.R. with A/C engines had trouble overheating in normal driving. That's why A/C was unavailable on the 68/69 models when A.I.R. was the bandaid fix for emissions in all states. Turbo overheating was stopped by the road running out. That's a true Benzinger story. He was one of the engineers working on it. You can only hold 120 for so long, and then they invented out west Interstates...😉 Many You Tube videos of his speeches. All other overheating was because of deferred maintenance! Just how many shop rags will the blower suck up was a common question back in the day.😆 What? You are supposed to clean the oil cooler like in the owners manual?🤔 1 Link to comment Share on other sites More sharing options...
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