Corvair Forum

I had a hard day at work, so to relieve some stress I came home and replaced my failing alternator. I read in a post somewhere where you can swap the housing from a 78 Camaro and used the internals for the Corvair. The Camaro alt being rated at 63 amps was just what I needed, so off I went to my auto parts store. The alt was only $35 with a $10 core charge which I will get back.

There are few reasons why I decided to go with with this alternator, one being the internal regulator, the second more amps, and third I want a "dummy" light. To complete this conversion I'm using the M&H kit #27555. I know the car works fine with the 35amp alternator, but i wanted a little bit more for my music and future upgrades.

This is a really easy mod that anyone can do, no hiccups at all, just plain easy, less than one hour to complete.

To Remove
1. Start off by removing the large nut that holds the fan/pulley.
2. Remove (4)5/16 screws from the back.
3. Carefully lift the top off by wedging a flat head screw driver between both alt pieces.
4. Take careful notice of where the bushings belongs, one below the fan and the other on top of the fan.

To Reinstall, just do the opposite of above.

Tools Needed:
1. 5/16 Hex Wrench
2. 5/16 socket
3. Crescent wrench for large nut
4. Flat head screw driver

Is this integral type? Picture not real clear on the plug.

Have done this change over several times and the pictures you have show it is not really difficult.

Thanks

Good swap details.

I have yet to need anything more than 35 amps so I just buy one off the shelf at Autozone. You still have to swap the fan but otherwise they are ready to drop in.

Some confusion here!!!

The STOCK Corvair alternator is designed to work with an EXTERNAL voltage regulator.

The 1978 Camaro alternator is an INTERNALLY regulated alternator which requires changes to the Corvair wiring to use. If you don't want to cut up the stock wiring you can use a kit #27555 from M&H Electrical Fabricators that has plug on adapters.

I've done several of the stock alternator (10DDN) to the internally regulated (10SI). You use the front 10DN housing, fan, pulley and install it on the 10SI main body. You also have to modify rear brace to fit on the 10SI housing (if you don't use the rear brace it will crack the alternator or oil filler housing).

BTW - As most know the Corvair alternator fan is unique since it turns reverse to all the other GM alternator fans and MUST be used to prevent high temperatures, and short life, of the alternator.

The other issue is UNLIKE the generator, none of the alternators used reverse threads on the fan and pulley nut. If you don't tighten the nut down properly with a lock washer it WILL come loose. Last year I helped a club buddy that had the nut come loose and it destroyed the alternator. To be fair the alternator was on his vehicle when he bought it so he was not to blame.

Jerry Whitt wrote:Is this integral type? Picture not real clear on the plug.

Have done this change over several times and the pictures you have show it is not really difficult.

Thanks

Yes this is an internal regulator, I plan to complete this conversion with a M&H #27555 kit.

66vairguy wrote:Some confusion here!!!

The STOCK Corvair alternator is designed to work with an EXTERNAL voltage regulator.

The 1978 Camaro alternator is an INTERNALLY regulated alternator which requires changes to the Corvair wiring to use. If you don't want to cut up the stock wiring you can use a kit #27555 from M&H Electrical Fabricators that has plug on adapters.

I've done several of the stock alternator (10DDN) to the internally regulated (10SI). You use the front 10DN housing, fan, pulley and install it on the 10SI main body. You also have to modify rear brace to fit on the 10SI housing (if you don't use the rear brace it will crack the alternator or oil filler housing).

BTW - As most know the Corvair alternator fan is unique since it turns reverse to all the other GM alternator fans and MUST be used to prevent high temperatures, and short life, of the alternator.

The other issue is UNLIKE the generator, none of the alternators used reverse threads on the fan and pulley nut. If you don't tighten the nut down properly with a lock washer it WILL come loose. Last year I helped a club buddy that had the nut come loose and it destroyed the alternator. To be fair the alternator was on his vehicle when he bought it so he was not to blame.

When using the M&H kit were you still able to retain your "dummy" light indicator, I really need to have this in my car? If so, how did you do it?

Charles - The 10SI is a three wire unit (just not the same position as the 10DN external regulator unit and the M&H adapter takes care of that) and yes it will drive the "GEN/FAN" warning lamp. Note: the light will not be as bright as the "TEMP/OIL" warning lamp since the alternator uses power from the lamp to drive the alternator energizing field. I've noticed GM compensated by using a lighter tinted lens for the "GEN/FAN" warning lamp. Point is - when you turn on the key the "GEN/FAN" warning lamp will be dimmer and that is normal. BTW - the wiring harness under the dash has a by-pass resistance wire in parallel with the bulb so if the bulb is burned out the alternator still gets power to "energize" at start up. Always good practice to check that the warning lamps illuminate when you first turn the key to "ON" before starting.

Charles - that unit you removed was NOT a 10DN, but a "single wire" unit that is a derivative of the 10SI unit sold by aftermarket places. It's good you replaced it with a true 10SI that has provisions for the warning lamp and battery voltage sense line. NOW - I would make sure the wiring is correct as I have my suspicions it may have been modified for the "single wire" unit you had on there.

66vairguy wrote:Charles - The 10SI is a three wire unit (just not the same position as the 10DN external regulator unit and the M&H adapter takes care of that) and yes it will drive the "GEN/FAN" warning lamp. Note: the light will not be as bright as the "TEMP/OIL" warning lamp since the alternator uses power from the lamp to drive the alternator energizing field. I've noticed GM compensated by using a lighter tinted lens for the "GEN/FAN" warning lamp. Point is - when you turn on the key the "GEN/FAN" warning lamp will be dimmer and that is normal. BTW - the wiring harness under the dash has a by-pass resistance wire in parallel with the bulb so if the bulb is burned out the alternator still gets power to "energize" at start up. Always good practice to check that the warning lamps illuminate when you first turn the key to "ON" before starting.

Charles - that unit you removed was NOT a 10DN, but a "single wire" unit that is a derivative of the 10SI unit sold by aftermarket places. It's good you replaced it with a true 10SI that has provisions for the warning lamp and battery voltage sense line. NOW - I would make sure the wiring is correct as I have my suspicions it may have been modified for the "single wire" unit you had on there.

VairGuy, that was a good observation because I never mention that it was a one wire alternator. I peeled back the tape on the harness and found three wires cut, "blue", "white", and "red" probably a size 10. All of these wires are hot when I turn the ignition to the on position, tested with circuit tester. I'm going to go ahead and connect the two wires from the kit to the matching color wires I found in the harness this morning.

LBC TITAN wrote:

66vairguy wrote:
VairGuy, that was a good observation because I never mention that it was a one wire alternator. I peeled back the tape on the harness and found three wires cut, "blue", "white", and "red" probably a size 10. All of these wires are hot when I turn the ignition to the on position, tested with circuit tester. I'm going to go ahead and connect the two wires from the kit to the matching color wires I found in the harness this morning.

O.K. blue to blue, white to white. The connector to the alternator is keyed so they go to the correct terminals.

Unfortunately someone has cut the wires to the old regulator socket. Hard to say whats going on and you'll probably have to unwrap the whole engine harness to figure it out. So I'll bet your warning lamp will still NOT work and the alternator field won't get energized properly.

O.K. hard to explain without a diagram - but here goes. Blue wire should go to "F" terminal on regulator socket, White wire goes to "2" terminal on regulator socket, Red wire goes to "3" terminal on regulator socket, Brown/White wire goes to "4" terminal on regulator socket. To run your setup F (Blue) must connect to 4 (White/Brown) and 2 (White) must connect to 3 (Red) - note the red wire is any one of the wires to the battery usually all connect at the frame junction block. The wires are shown in the factory manual, but it's not easy to read.

P.S. your sense line is open - do NOT run the engine like this or very high voltages could result.
Good luck.

Vairguy,

I understand what you're saying about the Blue wire should go to "F" terminal etc., but I believe M&H supply the adapter that will do that for me. See my pic below, great thought, I really appreciate it.

To check the voltage I used a multi-meter, black to chassis ground and red to battery terminal of the alternator, it showed 15.1. I'm going to test again at engine temp and see what the readings are.

Yes the rectangular black connector goes on the the plug that normally fits on the external regulator that is near the drivers side engine lid hinge, BUT based on your pictures the wires from your alternator to that regulator socket have been CUT.

Typically the 10SI internal regulator has an internal reference so if the sense wire goes open the alternator wont "run away" with a damaging high voltage. That may be why your seeing 15.1VDC. With a sense line to the battery the voltage should settle down to about 14.1 after the battery is charged up, or about ten minutes after starting the car.

Note that a lot of companies make rebuild parts and some of the cheaper stuff has design shortcuts, that why I said "typically".

Anyway it's time to find out where those cut wires are suppose to go and make repairs. If all else fails, you will need a new engine harness and M&H sells them.

Hi, I found an alternator online and wanted to make sure it would fit in my alternator housing. It is called LActrical and it goes on a big ole tnx yukon. It's a great price just want to make sure it will fit. It has externally regulator.

jmikulec wrote:

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Hi, I found an alternator online and wanted to make sure it would fit in my alternator housing. It is called LActrical and it goes on a big ole tnx yukon. It's a great price just want to make sure it will fit. It has externally regulator.

Craig replies: The pictures show a Delco CS-130, internally regulated alternator. What is shown WILL NOT fit a Corvair.

neat mod, when i was running the 140 i used a Saab 135 amp alt (i had to make one bracket) It worked very well, and dealt with the extra draw of an EFI system very well

I used a 10SI off an 87 Chevy Silverado. It is an 80 amp alternator. I ran my sense wire to the buss bar I put on the firewall. And my dtc lamp wire is hooked up to the connector on the alternator. It works great. I have EFI and a decent set of tunes, and I am never left needing any power. It charges the battery up pretty quick and the headlights are always bright.


Bad picture but I spliced the generator mount with the alternator mount brace for a 77 corvette, it has worked great for 2 years.

I checked the FLAPS and the 87 Silverado used two slightly different alternators. The 10SI 63Amp (typically used to upgrade the Corvair to internally regulated) and a 80 Amp dual foot unit that has a different rear housing.

The one on your car looks like the 63Amp rear case - nothing wrong with that of course.