GM one wire alternator for addition of electric fan on radiator for cooling

[John L.]

I have an early 1964 300 HP, factory Air Coupe, also power glide. I drive my car all the time and am replacing my original 55 amp alternator with a new 100 amp GM one wire alternator to provide extra amps needed for an electric fan mounted very discretely inside the radiator shell to keep the engine temp cooler. The one wire alternator has a built in regulator, and no alternations to the wiring harness was required. We wired it directly to the battery through a new cable (So we can put it back to original if we wanted to.)

Any thing we need to know about the procedure. I found nothing in the archives about doing this. But I have also found no way to keep the car cool in the summer running the air. Tried everything factory and resorted to this solution when nothing worked. Your comments are appreciated. Thanks, JFL

[Joe R.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Assuming that you are using the stock radiator? Let us know how this works on a hot day in traffic.
I have never been able to get a stock C-2 to cool on a stock radiator when adding AC. Always have had to go to the larger aluminum radiator with electric fans.
My only advise would be to go with the ignition switch to start the fan and not use the thermostat. Start it cooling immediately rather than wait for the fan to cool it down after temperature has peaked.
The stock radiator does not have any reserve cooling if the AC is added or stock.

JR

[John L.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Thanks JR. Great advice! We used the original factory numbered and dated original style (but new) radiator and added the electric fan inside the factory shroud. Still have cooling issues and the fan added too much juice for the alternator and battery. We heard a GM one wire alternator was the way to go on that.

We have considered a new aluminum radiator that comes with the fan built in and a sealed aluminum flat shroud...same company makes that one too. They say it is 40% to 60% more efficient and can be used with the existing factory shroud with minor alterations. I could live with that. We also are using our original fan (64 has that cupped configuration blade that is unique to 64), and we had enough room to do that in our set up now.

I think we may try the new modern radiator...hope we can keep the original fan blade too. Appreciate your comments on that. I'd say you are right on using a modern radiator. Thank you.

[Duke W.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

GM conducted thorough hot weather testing, and they did not "overheat". With a 15 psi pressure cap and a 50/50 mix of ethylene glycol/water, the coolant won't boil until 265F, and the normal operating temperature range is 180-230 F, with the upper limit being in extreme conditions like very hot weather stop and go driving.

But there's this myth out there than the engine should always run at 180. This is simply the minimum operating temperature established by the thermostat if the thermostat begins to open at 180. Emission controlled engines are usually equipped with 195 degree thermostats, which means they don't begin to open until 195F so the normal operating range is 195-230F.

Also understand that the themostat opens/closes gradually and is not full open until about 30 degrees above its rated temperature, which is the temperature that the thermostat begins to open.

Temperatures beyond this range are usually the result of cooling system components that are not operating as new to OE spec - a radiator that is loaded with deposits that reduces heat transfer capacity, an out-or-spec fan clutch or a modern replacement that is "tuned" to the radiator exit air temperature of a 195 degree thermostat, an incorrect fan for the application, or a problem with the spark advance map like a dead VAC and/or insufficient initial spark advance.

Guys spend untold time and dollars chasing these supposed "overheating" problems, often filling up the car with aftermarket parts and snake oil when there may be no problem at all, or there is simply an out-of-spec or incorrect component that needs to be rebuilt or replaced with a new component that meets OE spec.

Duke

[Domenic T.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Duke,
Just curious about how and what the ambient temp was during the GM tests? Hope not at 72 degrees and sea level.
Back in the early 70's I talked to a tech rep at Mobile sat to their noise level tests, multi grade vs straight. I was taken back when the said their tests were at 250 degrees for all their tests.
Oil temps under the pistons and in the crankshaft were much higher than 250 but that's how they did it. By the way the noise level test was higher on the multigrade oil. TV had a test using running engines to show how much better one oil was over the others once the oil was removed. Funny that all the engines had fan blades and no radiators.
There was a accidental test done in the 50's we did by draining the oil on a solid lifter 6 cylinder. The bone yard would only give 25 bucks for a running car and 15 if not running. My friend drained the oil and we followed him to the yard so we could push him the rest of the way. He was not going to give them a good engine for the 10 bucks extra. We drove about 6 miles and the engine was still running so he drove past the yard for a few more miles then said he was going back to the yard. He got the 25 bucks for a running car that didn't have a drop of oil in it. True story, I was the car behind.
I question tests and have found some amusing. I have found, and proven hydraulic lifter tests in the aircraft manual to be wrong. They were done in the non operating range of the lifter and have failed them. Also ordered 20 from continental and sent them back red tagged (not approved for use), only to get a lengthy phone call and appreciation of the test method I developed. I have watched oil company videos ( aircraft) and couldn't believe my eyes.
My new 65 SS ran hot, 327, when the ambient rose and remember turning the engine off crossing the border in TJ and we pushed it as the line moved so it wouldn't overheat.

DOM
DOM

[Duke W.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

GM does most of their hot weather testing in the summer at the Mesa, AZ proving grounds. Sometimes they also do hot weather testing in Death Valley during the summer.

Duke

[Joe R.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Several NCRS members including myself have done extensive hot weather testing on AC Corvettes. They all failed the test!!!! But then again, they were not for sale!!!!

JR

[John L.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

I appreciate the replies. I am committed to the electric fan, and perhaps the high performance radiator, and from what I have found, I will need more amps than my factory original restored alternator can yield to run the fan, the AC, blower, etc. Anyone ever installed the GM one wire 100 amp alternator with built in regulator? Is there any thing I need to know about doing that? Thanks.

[Keith B.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Why don't you upgrade the internals of your original alt to handle the amps needed

[John L.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Keith, thanks! I did call the NCRS member that rebuilt it for me...he said that couldn't be done. That's a great idea though...you know anyone who can do that? I'd love to run the original!

[Duke W.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Delco alternators are configured from a family of interchangeable parts, and current ratings are usually determined by the rotor windings. I believe the only difference between the base 32A and 55A units on early C2s is simply the rotor, and if no other higher output rotor is available for that early alternator design, then 55A is it.

The OE 55A alternator may be sufficient depending on how much current the aux. fan draws. The test is to load it up at idle in Drive with service brakes applied, lights on (high beams), and every electrical device on including the AC compressor clutch and the aux. fan. If voltage doesn't drop below about 12.5, then it's probably okay unless you spend a lot of time idling with everything including the high beams on.

The fan should be wired through a relay with a power wire and fuse of sufficient capacity for the rated fan current, and the power wire should be connected directly to the alternator output stud (or battery). This way the OE wiring will only see the relay current and won't be overloaded.

Duke

[Joe L.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Why don't you upgrade the internals of your original alt to handle the amps needed

Keith------


I don't know of any way to get a series 10 DN alternator (as used for all 1962-68 Corvettes) to a rating above 61 amps. If kits are available for this, I'm unaware of them. Even if kits are available, I'd be very concerned about the reliability of any alternator so-modified.

[Domenic T.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

As Duke was saying (family of parts). I did the trick on my alternators by simply taking the stator and Roter from a 61amp and installed Them in my correct numbered case.
Makes one think, why have the lower amp ratings when the cost of building the larger amp version should be the same, or a few cents different. Battery size was the same!

DOM

[Peter M.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Hi John,Your alternator should be a 10DN series. They are a pretty reliable and trouble free unit. The problem is their output at idle is less than ideal even if upgraded. If you do an internet search for 10DN alternator I think you will find options that you could consider as well as the one wire. Try and get output curves for all the choices you are considering and don't forget to add up all the electrical loads that your car requires for comparison. Regards, Pete

[John L.]

Re: GM one wire alternator for addition of electric fan on radiator for cooling

Thanks to all! We have multiple directions to consider and I will post when we decide.... And if it works! I have 40 degree air coming out of the original rebuilt C-6 compressor using R-12. I just need to figure out how to keep the engine temp cool!

Has anyone tried the factory fit modern radiators that even offer the built in transmission cooler? They have a fan system and sealed shroud that allows my factory shroud to fit over it all and enough room to leave my original 64 unique fan in place. That looks like a viable solution to really keeping the car drivable in about any situation, and still looking stock at at glance. Thoughts? Thanks again!