CrCrzy

I finally got my 1960 Corvette fired up for the first time in 7 years since I took it apart in 1999. Completed the wiring upgrade to an internaly regulated alternator, 3 wire hook up, 63 amp. Got the car to start up but when I turn the key to shut her down she keeps running. With the key still off I pulled the white two blade plug off the alternator and she shuts off. A little background on the alternator upgrade, I used the input side of the ballast resistor, Acc hot, to excite the alternator upon start-up. I am guessing after I shut the car off, because the alternator is still producing current for that fraction of a second it is sending reverse current back to the ballast resistor which in turn lights the points and keeps the car running. Am I correct in this assumption? How have some of you guys who have performed a generator to alternator upgrade wired the alternator? I am still using the original charge wire and connecting it to the alternator stud. Only new wire is the excite wire which I originated from the ballast resistor. I fixed the problem last night by running a relay to the alternator. Acc hot from ballast resistor to turn on relay, relay output to alternator. This worked but I am still trying to find a conventional way to fix this. After I fixed this problem I noticed the ammeter reading full negative (-) 30. I crawled under the dash switched the wires pole to pole and now full positive (+) 30. Is this normal on a solid axle with an alternator upgrade? I haven't ran a volt meter on it yet to see if my alternator is overcharging and my internal regulator is shot. Again, for those of you have performed a similar swap, what is your ammeter reading after the generator to alternator swap? Any help will be greatly appreciated. Thank you.

INMYBLOOD

I put a 1 wire alternator on my 58 and it worked right from the start. It was only like a 45 amp unit and I under drove it. There is not much in my car to draw current. It does not come on until the first time I crack the throttle. Do you need to supply it with the inital charge? Mine will show full current at start up if it has not been started for some time. If I upgrade to a alternator with more amps I wonder about damaging the gauge.

rene-paul

You mentioned 3 wire hookup. batt terminal hot all the time and a wire you added from the ballast to the two wire plug. where is the third wire? what happened to the original field excitation wire for the old gen? That should be switched power and could be used for field excitation which will be the F terminal on the two wire plug on the new alt. the other terminal is R, what do you have connected to this terminal? If you have a Delco 10 or 20 SI [sounds like a 20 SI], try this: remove the 2 wire plug and disconnect the ballast wire you instld. leave the batt wire connected on the alt and make sure it reads batt voltage. Install a #14 wire from the batt terminal on the alt to the F terminal on the two wire plug and install. nothing on the R terminal.
Pls disconnect the neg side of the batt when working on the alt.
fire her up and report back, remember, the purpose of the alt is to keep a GOOD batt charged.

John S 1961

WWW.madelectrical.com

I have the same (almost) set up but added one of their terminal blocks and then ran the charging wire per the stock way through the ammeter. I also added the reccomended "shunt" across the ammeter terminals (per Mad's reccomendation a 6" 14g jumper from the ammeter terminals) the ammeter works seeming y correctly now as ALL the current doesnt need to run through it. I also added the relays for the lignts and that IS REALLY GOOD! I removed the ballast resistor because I have a HEI distributor (another great thing) and put the terminal block in its place.

On other cars which had the runon problem I added a diode to the exciter wire.

CrCrzy

it is a 10SI alternator. On the factory wiring their isn't an excite wire for the generator. It is internal to the generator. The only wiring from the car harness to the generator/regulator assembly is the main charge wire. The rest of the wires just connect the regulator to the generator. The three wire hookup I am trying to explain is: first wire, main charge wire. Two wire plug contains the second and third wire. It was purchased from Pep Boys as an alternator plug repair kit. The two wires coming out of this plug has one 18 gauge white wire, and one 14 gauge red wire. The 18 guage white I am using as an excite wire originating from the ballast resistor. The 14 gauge red is my voltage sensing wire. I should have connected this wire to my underhood junction block but instead for the time being just connected it to the back of the alternator stud. I did not change the wire orientation on the two wire alternator stud, so unless Pep Boys messed up when assembling the plug with two wires I think I have the basic concepts covered on how I wired the alternator. I was just wondering who out there has installed a 10SI alternator on their solid axle and how they wired it. I chose to stay away from a one wire in the event the alternator fails and I need a quick replacement. I have fixed the alternator problem somewhat but like I said, I don't feel that wiring in a relay is a conventional fix. It works but there has to be an easier way. The problem I am most concerned with is the ammeter reading. The only electronics on the car that are hooked up is the starter, alternator, and ignition system. I left all the fuses out of the fuse box upon initial start up so I could minimize any variables if any problems came up. That way I could localize any problem to the three systems that are wired up. A little background to the "upgrades" to the wiring harness that I have made. Instead of routing the main charge wire directly to the ammeter from the generator/alternator, I cut it at the firewall and installed a junction block. From the junction block I installed an inline fuse connected to the other half of the main charge wire. This half of the main charge wire would normally supply voltage to the ammeter, which then supplied power to the ignition switch and fuse block. I instead installed another junction block under the dash to bypass the ammeter. That way I would not be running my entire car off of a 47 year old ammeter although it has been rebuilt. To show charge on the ammeter, I ran a 12 gauge wire from my underhood junction block to the input side of the ammeter. The outgoing wire from the ammeter is still the factory wire routed to the battery terminal on the starter. This wire also now has an inline fuse protecting it. I have checked and double checked this wiring and feel it is a good set up. I just can't figure out why the car continues to run and not shut off, and after I fixed that with a relay, why the high amperage reading on the ammeter.

INMYBLOOD

Does it have an electric fan on it????? I've seen people hook up a fan to the hot side of the ignition and it would run on... but I think it was a tapering down kind of running.

CrCrzy

John S 1961, Thanks for that reply. So this "runon" problem I am having isn't a one off situation? You have encountered it before? What is the function of a diode, and could you please explain what a shunt is and how you wire it into this system. I am glad you replied to this, I feel like I am getting closer to a resolution. Thanks

StickShiftCorvette

I have a three wire SI altenator on my '61.

I wired it EXACTLY as it would be in my '69 per the Chevrolet service manual. The only trick was figuring the right resistance for the voltage sensing wire.

I used a 40A alternator. If you use a 63A alternator you should run a wire in parallel across the amp gage so you do not burn it out by forcing too much current through it. Again, you need to make the wiring look like the amp gage on a later model Corvette ('69 will work).

CrCrzy

stickshiftcorvette, where did you hook up your excite wire from?

I spoke with Mark from Mad Electric after John S 1961 recommended. By the way, I have been reading some of your old posts John, and I think I am actually building a duplicate car to yours without intentionally doing so. Back to Mark, talk about smart. He explained the shunt and diode to me today. Diode is similar to the function of a back flow preventer valve on the plumbing of a house. One way circuit. He said to use one inline on my excite wire, however he said the relay will also work. The shunt like most of you were trying to describe to me, is a parallel circuit that is basically a jumper wire connecting the two posts on the back of the ammeter. Wiring parallel will split the amps between the shunt and the ammeter. He said he used to include the shunt in his alternator conversion kits but no longer does so because he recommends replacing the ammeter with a voltmeter. However, I do not plan on making the change so I guess I will have to stick with the 6 inch long 14 gauge shunt/jumper wire between the two terminals of my ammeter. Thanks for the help guys

rene-paul

I checked the R to F terminals on 10 SI with an ohm meter and had 46k ohm. If your volt sense wire to the R terminal is hot with the ign switch off, volt/current will flow back to the F terminal back to the ballast wire feeding the coil thus keeping the eng running.
A diode is an electrical check valve that will flow volt/current in ONE direction only. So you can place a diode in the ballast wire feeding field excitation. with ign sw on volt/current will flow to field excite, BUT will be CHECKED from the volt sense with ign sw off, thus stopping eng run with ign off.
IMHO I would not have field excite powered from the ign wire.
stick shift MAY have the best solution with the 69 wiring set up.
brgds
rene

CrCrzy

I have the wiring figured out now. Intead of using a diode on the excite wire, I wired in a relay and the ignition system shuts the car down when the key is shut off. Also, I am no longer using the input side of the ballast resistor to excite the relay to the alternator. I found and alternate Acc hot lead.

Only problem left to do is figure out why the ammeter pegged out. Mark at Mad Electric told me that the wiring as I explained to him is correct in my car. Only problem is, as he says, most batteries bought at the store, even if brand new are not fully charged. My system is sensing this and is sending full charge to the battery to top it off. He recommended slow charging the battery and reinstalling. Also, like others have said and what I said in the previous thread, I need to install a shunt to split amperage load on the ammeter.

John S 1961

the guy knows his stuff and has obviously been down the old car road plenty of times. You will do alright following his proven methods.

Tampa Jerry

Just to be safe, if your amp guage is still reading 40 amps after changing your battery, put a volt meter on the alt. and check voltage at the back of the alt. and at the battery. Do this with the engine running. If you are putting out over 14+volts, your voltage regulator may have gone south. I cooked my regulator before I realized I needed a resistor/diode in the switched line going to the alt. Mine was putting 16.75 volts at the battery. Jerry