Hey guys. For my 68 resto, I ended up buying a new drivebelt accessory package, which came with a new alternator, but was relocated to the pass side. I extended the harness, but the new alternator looks to have a newer style connector. So at this point I have 3 options:

Cut the OEM connector off and put spade on the ends and plug it directly to the alternator.
Make a jumper harness by finding the correct plug for the alternator and plugging that into the existing harness.
Splice the newer, correct plug onto the existing harness.

Questions would be: does the blue/white wire matter which side it connects to on the alternator? Or are they interchangeable?

Where does the pictured brown wire go?

The green wire appears to be the temp sensor wire... I assumed it would be some sort of ground so I extended it to the pass side as well. Welp, since it's now on the pass side, any ideas on how I should go about utilizing it?

I'm also setting up a Dakota digital setup if that matters as far as gauges.

Thanks for any leads!

 

Your car has a external voltage regulator and the alternator in the picture looks to be an internal voltage regulator alternator. So you will not be able to use those wires. Is this a one wire alternator? Then you don't have to do anything but tape up that connector and tuck it away. If not, you'll need to extend the voltage regulator #4 terminal wire (excite circuit) to the #1 terminal on the new alternator and extend the voltage regulator #3 terminal wire (voltage sensing) to the #2 terminal on the new alternator. You can also lose both the blue and white wires as they will no longer be needed.
Edit: the green wire is probably for the temperature sender. Don't know what the brown is for.

 

Thanks! I didn't realize external regulation was a thing haha, this is my 1st classic I'm working on (can't wait to get to carb questions!). But yeah, you're correct...I see the box on the side of the fender now. Would something like this for the trick?

Conversion kit
As far as the temp sending unit. What temp is it actually sensing?
I'll try and dig further into that brown wire.

 

Yep, no wiring involved with that. Just plug in and go. I didn't know that they made that conversion kit. Just make sure that actually is an internal voltage regulating alternator.

 

Found this video if anyone ever had any questions -- pretty straight forward
I bought that kit off ecklers but could have also done it this way!


As for the green wire, I'm going to eliminate it (cover it in the bundle) since I have the Dakota digital temp sensor. Still looking into the brown wire, but it's looking like it may be eliminated as well.

 

Just to verify I'm doing things right so I don't burn my house down 😆 --

I found the alternator I have is 120amps, so I'm going to run larger (4 gauge) wire. I'm going to:

Run a cable from the alternator to a junction block I'll mount.

From the block, run 4 gauge to the starter. The starter has the OEM cable that runs to the battery. I'm going to leave that cable alone, as I've read it's thick enough. I'll use the junction block to run my electric fans and headlight motors eventually. I'm going to keep the OEM red wire connected at the alternator and down at the starter so I don't have a loose wire/need to modify the harness anymore.

Run a ground cable from the back of the alternator to the engine block, where the chassis ground is also located. The chassis ground has a second wire which I think runs to the housing on the starter (correct?)

For the existing external voltage regulator, I was going to use the eckler kit, but the connector on the harness was damaged. So I connected the blue wire to the brown/white wire, and the red to the white wire. At the alternator, I'll use the other half of the eckler kit to complete the 3 wire circuit and convert my old style connector to the new style one.
I'll do away with the green sensor wire and the brown wire, which was for the generator sensing/light.

I think that's it. Am I missing anything? Thanks!!

 

Lectric Limited makes an adapter for the new alternator using the original external type alternator plug that does the wiring "trick" all for you. They offer lots of useful stuff when updating your Corvette's Alternator. Here is the information:

Alternator Conversion Harness Kits

Part #VAK6368SI
Now you can upgrade your alternator/generator and not have to cut or splice into your original wiring harness!

Just for your information if you use Marine Grade wire it is frequently more flexible than ordinary automotive grade wire is and it has a better quality of insulation on it. I did the switch to a 120 amp modern alternator and used the Marine Grade wire and it was so much easier to run and make the turns than regular car wire. I also used the Marine Grade Heat shrink over any connections as it has a heat activated glue inside it that seals the connection even better than regular heat sink. I simply ran the output wire to the starter motor Battery connection making it simpler. I then put a Marine Circuit Breaker in the battery line where it connects to the battery itself. One button disconnects the battery from the rest of the car. Having a Boat teaches you to make connections that last in wet environments.

If you really want the connections to work and last longer Dipping the crimped connector on the 4 gauge wire into a solder pot full of molten solder really makes the connection so much better. I used to build large PV Solar systems and we dipped the ends in the solder pot to ensure they would last even in wet, remote locations. Once dipped they cannot loose or degrade the connection to the crimped connector as it is sealed inside the solder. Oxygen just can't get in there to mess up the connection.

Best regards,
Chris

 

Appreciate it! I'm literally working on the car as we speak. I went with the same wore and heat activated ends. Everything is sealed up nicely. I'm just not sure if I needed to run a new cable back to the battery not. I read that it's already 2 gauge, and I'm using 4 gauge, so it'd be a downgrade.
I have a fuse and 125amp fuse that I can put in line but not sure if people were doing that or not. I planned on fusing any of my external accessories like the fan.


Also, if anyone wants to chime in, where does this ground go? Pass side, connected to the motor mount bracket, I believe it mounts to the lug sticking out of the starter but from my reading I couldn't verify that. Thanks!!

 

On my 82 the ground cable goes from the motor mount frame extension to a motor mount block bolt.

 

A starter mount brace connects from the starter bolt to the block and the black ground wire connects with the brace on the block and then to the frame.

 

I used the engine for a ground as I found a convenient hole with threads to use for the ground. You do not need to run any further than the battery wire at the starter motor with your #4 wire.

A fuse in the alternator output is not really necessary but since you are planning on a Junction box for accessories you might want one between the junction box and the starter motor. One point however, be very careful how and where you put a junction in with full battery voltage/power available at it. If for some unforeseen reason you are involved in a front end accident you don't want something to short your full battery power into the many nice grounds available up there. The C3's did not have any fuses in the battery positive line supplying the starter since the old starter motors can pull several hundred amps when hot and working their hardest. I would have a fuse between your accessories and the battery power, just to be safe and protected.

When I installed my 120 amp alternator I went ahead and ran a #4 wire to the starter like you did. It has worked great for me. I have added my dual Electric SPAL fans, a PWM electronic fan controller and my Holley EFI system. Most accessories like the new EFI system want you to power them off the battery itself. My PWM Electronic Fan controller also wanted a good solid battery positive connection. What I did was to install a new Fuse Block under my dash panel on the passengers side. I then ran a #4 wire to it from the battery powering the accessory fuse block. Now I have my radio's amplifier and numerous other items powered at the second fuse block. My EFI system is directly powered off the battery and I have a Flooded Lead Acid battery "Deep Cycle" battery in the car as the primary battery to allow the fans to run for 1/2 hour post shutdown if needed without any damage to the battery. I have a gear drive starter on my 12.25-1 Compression 427 so it draws a lot less than it did from the factory. You clearly need to have a fuse between any accessory and the battery. My second fuse block is fused as well but the entire car's power goes through the marine grade 200 amp Circuit breaker that I can easily open to stop the discharge of the battery when not being driven. My battery is secured to the floor and the battery compartment is insulated from heat as well. The overflow tube is extended to allow excess battery electrolyte to drain out on the ground below the Corvette.

Before you get ready to wrap things up without the external voltage regulator that our cars came with you need to be sure that your Horn relay is getting power when the engine is running. I had a fan controller that went bad (and let the smoke OUT) and this killed one of the two fusible links coming up from the starter area. It was attached to a fuse in the car's fuse block but still managed to burn out one of the fusible links. I now have power at the Horn relay which keeps the fuse block powered and the amp meter working. Be very careful near the Amp meter as it originally had full battery charging current going through it and can short out and start a fire very easily.

You clearly do not want to have your 120 amp alternator charging through the 0-40 amp ammeter and with your new charging wire going directly to the starter the ammeter will not be accurate anymore. I put vacuum caps over the ammeter's studs and verified that everything is protected from loose insulation shorting the posts out. Under the dash you will also find a Nylon Oil Pressure Line feeding your oil pressure gauge. I don't like the idea of 200* engine oil leaking or shooting out from under the dashboard. I replaced my nylon tube with a -3AN SS Braided Hose that feeds the oil pressure to the gauge from the engine. I got burned when young riding a road racing motorcycle when an oil line broke and shot VERY Hot oil on my right leg resulting in a scar to this day 50 years later. Call me paranoid....

The suggestion of the marine grade wire is not so critical but the better quality Marine grade heat shrink makes a huge difference. Trying to remove the marine grade heat shrink is a job with the heat activated glue. I basically stopped using the automobile grade cheap heat shrink. It is worth the extra cost which is negligible anyway. The idea of putting all crimp on connectors in a bath of molten solder in a solder Pot is a great way to prevent electrical issues. Unfortunately most guys don't have a solder pot in their garage. I have one that keeps about 1 cup of solder liquid when in use. It can be very dangerous with young kids or careless adults around when in use.

When you stop using the external voltage regulator you are changing the wiring pretty substantially. Be careful and be sure that you have power going to the points the Voltage Regulator sent it. When I did this swap to my early 1968 I didn't have anything flowing through the dashboard and the ammeter was virtually dead. You need power going through this path but you do not want the full 120 amps going through that ammeter circuit. I would love to hear how you solved this issue. I spent a lot of time looking at the schematic of the 1968 Corvette before making my mind up. I would love to replace the ammeter with a good Volt meter showing me the battery voltage accurately.

I hope that your installation went well! That extra power from the alternator sure helps keep the battery charged up. Once you start driving much be sure that your battery doesn't use too much electrolyte, bigger alternators can keep the battery voltage higher which uses the electrolyte's water up and it might need to be replenished with Distilled water from time to time. I ONLY use batteries that allow you to add water to them as they use it.

Best regards,
Chris

P.S. When you add a fuse to the charging wire don't use the same size fuse as the alternator is rated for. I would put a 150 amp fuse in place of the 125 amp fuse. IF the alternator ever put out full power it would blow the fuse. The one thing you never want to do is to run an alternator without a battery connection.

 

I saw this diagram, but I don't recall having a starter bracket. When I bought the starter last year I got the wrong one because apparently there are two different styles of starter for this motor (396) and I think I had one that only had 2 bolts that mount directly to the block. I snapped a picture during my teardown and so happened to catch where the 2 wires went previously, and they were both connected to the starter bolt you can see in my picture, but I wasn't sure if that was the proper placement -- I'll try and add that picture if I can find it.

 

I am sorry for telling you things that you already know far better than I do. I am an Engineer but Mechanical and my experience with electrical stuff came from working with Westinghouse Electrics Nuclear and Advanced technology branch. We built large Remote Power Systems using our own computerized Controllers. It took me a while but I learned a lot. Everything went someplace very remote where it would cost a lot to get there to fix them. The toughest job I ever had was working on a Cellular system in the U.A.E. out in the desert where the project manager built everything with negative ground. As you probably know the Cellular equipment uses positive ground. The company would not let me turn the systems off while I rewired it or face a $10k a minute fine and forfeiture of my passport until fixed and paid. I had to come up with a way to keep the 5000 amp hours of 48 Volt Battery power under wraps while I rewired the entire control system. I got creative and used battery jumper cables to power the system while I removed and rewired every control system. One wrong touch and I would have been fried. Made me respect electrical power a whole lot better. Playing with individual 2 volt battery cells that use more than 5 gallons of electrolyte per cell I have learned to be really careful.

The point I was trying to make was that after installing the new alternator in my car I simply ran the #4 wire from the alternator Output to the Starter motor's battery connection. This is where the #2 wire comes from the battery to the starter supplying power. You probably could teach me a lot regarding sizing of fuses. What I ran into was the original path of the output from the alternator went into the Horn relay and from there to the ammeter and the fuse box. I could start my Car but had no power to my dashboard. The ammeter was now out of the circuit and no longer of any use. I have a relay that energizes the dashboard and fuse box and that seems to work well for me.

My engine is the 427 that my car was built with initially as it started life as a L71 Corvette back in October of 1967. There were several threaded holes in which I could attach the ground wire. Having a good ground strap to the engine never hurts anyway. I am amazed at the number of problems a bad ground to the engine block can create, I see it more on the C4 Forum as I help folks there as well. I took the 427 and built it into a L88 (replica) and really enjoy the 0-60 in less than 3 seconds times I have been able to get. Unfortunately traction is now the bigger issue and breaking loose at speeds is another new danger from the extra power being made. My car still has the one ground wire coming from the battery and connecting to the frame below the battery area. As long as you have a good solid ground at your engine block it is not too important where you ground it. I tried to keep the number of wires added to a minimum.

The Dakota Digital dashboard must be a nice feature! I have recently installed a Holley Stealth Sniper on top of the L88 and am planning on using the Can-bus system to install a 7" screen over the center panel in the dashboard. I am going to have the important numbers displayed there and program the car to shut down if I loose oil pressure. I want a Fuel pressure gauge and such so using the single wire to connect them in piggy back will be a nice feature. Being color blind makes wiring just a bit more fun, so the fewer wires the better.

As far as fusing the junction block as I mentioned I simply installed a second Fuse block under the passengers dash pad. This is wired to the battery and allows individual fuses for each item added to the car. I have a bad back (five crushed discs) so working with the factory fuse panel is a bit tough for me. I have been very careful not to create ground loops or anything while doing this. I had thought about putting a fuse box under the hood but chose not to after thinking about the consequences in case of an accident. Under the dash there is plenty of room for me as I don't have Air Conditioning. The Higher HP big blocks were lucky just to get power steering and power brakes. I switched to a Steeroids Power Rack and Pinion and that was a great upgrade. The EFI system was the biggest change I have made but I still have my collection of five or more carburetors that I used on the 427 over the years. Every change I make on this Corvette is reversible. I have not cut up or done anything permanent to the car. My daughter is an Aerospace Engineer and she wants to inherit the Corvette when I am done using it. She will have every part I have removed all bagged and tagged. My car did come with the factory T.I. system and for that I pulled the parts had them overhauled by the T.I. Guru Dave Fiedler before bagging them up and storing them. I have been using a MSD Billet Distributor and MSD 6AL to drive my ignition system. The timing control is now done by the Holley Stealth Sniper. I really want to connect my MSD knock sensor system to the Holley EFI system software. It has a couple 0-5 volt inputs that I can use so I need to get creative and figure out a way to do it. The newer Holley Terminator systems have provisions for a knock sensor. I already have a way for the EFI software to control the water/methanol injection when the engine gets really Hot. A little technology sure can help these older C3's

I hope that you enjoy your 1968 Corvette and all the nice features you have added! If you have any questions at all please feel free to PM me or just post your questions. Have a Great Memorial Day weekend!

 

You don't have to apologize for anything haha we're just having a general discussion! I appreciate all your insight and all the info you've given me. I'm pretty close to wrapping up the project -- looking to get it up and running by the 4th of July hopefully! Thanks again! If I have any questions I'll definitely shoot you a PM!