12V for electric auxiliary cooling fan

[Jimmy B.]

I have finally thrown in the towel and am installing an electric cooling fan in addition to the stock 7 blade fan on my 65 ac roadster. Yes I have a new DeWitt radiator. Yes I changed the distr. vacuum pot to the correct one. Yes I set the timing at 10 deg. Yes I tried 2 different 180 thermostats then no thermostat. Yes I purchased a "new" 7 blade fan and tried that. I also made sure the dimple on the distributor gear was oriented correctly and moved the distributor 1 more tooth over, Yes I tried 2 NOS fan clutches. Yes I changed to Zerex G05 with distilled water. Yes I changed carburetors - 2 different 3720SB's, Car finally idles at 180 deg. but as you start driving especially in stop and go the temp goes higher and higher. I also put in a manual temp gauge and saw same effect, IR gun showed the same, so since I am out of options I am going down the aux electric fan route. My car is an auto with ac so that condensor (new) really blocks the fresh air to my radiator.

One question I have is while installing the auxiliary fan there is a "heavy" gauge red wire marked battery. Does anyone know if I can run this to the BAT on my alternator vs my + bat post?

Thanks in advance.

Jimmy Blakely

[Michael W.]

Re: 12V for electric auxiliary cooling fan

but as you start driving especially in stop and go the temp goes higher and higher.

How high does it get?

[Don H.]

Re: 12V for electric auxiliary cooling fan

I have put many miles on a '64 & '65 300 HP, Auto with Air in many conditions. They will get hotter and sometime you just have to turn the AC off. I would be very interested in your results using an auxiliary fan, please keep us posted. Thanks, Don H.

[John L.]

Re: 12V for electric auxiliary cooling fan

Good idea as you have tried most everything else. What about the alternator ??????

[Frank D.]

Re: 12V for electric auxiliary cooling fan

I hook my accessories to the horn relay buss.... If you spend some time reading on the Mad Electric web site in their tech section you'll see why.... These early GM cars use remote sensing to regulate alternator output and going directly to the battery has several disadvantages; one of which is your ammeter gauge will read incorrectly... http://www.madelectrical.com/electri...evymain2.shtml

You could try one more thing for around $40; a Hayden 2747 fan clutch. These operate at a higher percentage of full fan speed, come in to play sooner, etc.. Could be the 'edge' you need...

[Jimmy B.]

Re: 12V for electric auxiliary cooling fan

I am getting 220 maybe 230 deg NOTE: I am not running my AIR COND at all, this is just going to a car show in Sarasota, car was hot when i got there at 7:00 A.M. it puked a little fluid out, when I left at 3:00 P.M. and hit stop and go traffic it got even hotter not quite hitting 240 deg on my temp gauge by the time i reached home. Total drive 1 way approx 20 - 25 mi.

[Jimmy B.]

Re: 12V for electric auxiliary cooling fan

my alt. is the correct unit rebuilt by Pirkle and it does have the original smaller fan pulley that is correct for my application.

[Frank D.]

Re: 12V for electric auxiliary cooling fan

I reread all the things you changed but two add'l thoughts...did you verify your bottom radiator hose isn't collapsing, and, how do you feel about the condition of your water pump -- I didn't read where you had done anything with the pump..

[Joe R.]

Re: 12V for electric auxiliary cooling fan

Jimmy,

With the exception of putting a larger aluminum radiator with a couple of electric fans on thermostats 240 is about right in Florida this time of year for a 65 on AC. You might try changing the tires, rims and holding your breath (joke). It aint gonna get any better!

JR

[Gene M.]

Re: 12V for electric auxiliary cooling fan

I reread all the things you changed but two add'l thoughts...did you verify your bottom radiator hose isn't collapsing, and, how do you feel about the condition of your water pump -- I didn't read where you had done anything with the pump..

Frank may have suggested a good culprit to check out. The rebuilt pumps are known for using replacement sheet metal impellers. Not good for circulation. An original cast impeller with a side face moves water better. Water pumps are not very efficient to begin with and having sheet metal impeller just makes it worse.

Adding electric fan is a cover up as when new these cars ran just fine without them. Is the engine rebuilt? Does it have a big over bore? Having thin casting walls does run hotter. Is there big temperature difference between engine and radiator when max hot?

How much air is getting thru the condenser to cool the radiator? Condenser original/ replacement? Are all the gaskets in place around the shroud? Is the fan blade half way inside and outside the shroud?

[Joe L.]

Re: 12V for electric auxiliary cooling fan

I have finally thrown in the towel and am installing an electric cooling fan in addition to the stock 7 blade fan on my 65 ac roadster. Yes I have a new DeWitt radiator. Yes I changed the distr. vacuum pot to the correct one. Yes I set the timing at 10 deg. Yes I tried 2 different 180 thermostats then no thermostat. Yes I purchased a "new" 7 blade fan and tried that. I also made sure the dimple on the distributor gear was oriented correctly and moved the distributor 1 more tooth over, Yes I tried 2 NOS fan clutches. Yes I changed to Zerex G05 with distilled water. Yes I changed carburetors - 2 different 3720SB's, Car finally idles at 180 deg. but as you start driving especially in stop and go the temp goes higher and higher. I also put in a manual temp gauge and saw same effect, IR gun showed the same, so since I am out of options I am going down the aux electric fan route. My car is an auto with ac so that condensor (new) really blocks the fresh air to my radiator.

One question I have is while installing the auxiliary fan there is a "heavy" gauge red wire marked battery. Does anyone know if I can run this to the BAT on my alternator vs my + bat post?

Thanks in advance.

Jimmy Blakely

Jimmy------


Use fan clutch GM #88961768, aka Delco 15-4950. To use this fan clutch you need to also use the following:

1) 5/8" ID-to-3/4" OD bushing for waterpump pilot shaft (may be supplied with the fan clutch or can be purchased at a hardware store)

2) 1971+ fan blade assembly GM #469580 (18-1/2")(discontinued) or GM #342715 (17-1/2"), These are both 7 blade fan assemblies.

The above will do you better than an electric fan.

[Jimmy B.]

Re: 12V for electric auxiliary cooling fan

lower and upper hoses new from L.I. Corvette and the lower one does have the spring/wire winding inside it. waterpump is the correct rebuilt one but I did not take it apart to look inside.

My engine is the original with a .060 overbore totally rebuilt with flat top pictons less than 500 miles ago. I have changed the oil and have Shell Rotalla in the crankcase. The camshaft is totaly stock with hyrdraulic lifters.

[Gene M.]

Re: 12V for electric auxiliary cooling fan

lower and upper hoses new from L.I. Corvette and the lower one does have the spring/wire winding inside it. waterpump is the correct rebuilt one but I did not take it apart to look inside.

My engine is the original with a .060 overbore totally rebuilt with flat top pictons less than 500 miles ago. I have changed the oil and have Shell Rotalla in the crankcase. The camshaft is totaly stock with hyrdraulic lifters.

A .060 over bore will run hotter to some extent.

[Duke W.]

Re: 12V for electric auxiliary cooling fan

Yes I changed the distr. vacuum pot to the correct one. Yes I set the timing at 10 deg. Thanks in advance.

I don't recall if this was specifically covered in other threads, but you should have a B26 VAC. Is that what it is?

You should set the idle speed/mixture at about 500-550 IN DRIVE WITH THE AC COMPRESSOR ENGAGED. How is it currently setup?

Total idle advance with 10 initial (and VAC connected to a full manifold vacuum source) should be about 26 at the above idle condition. Have you checked it?

Also, I would like to know the manifold vacuum value at the above idle characteristics.

With a 15 psi cap (Have you checked yours with a cap pressure tester?) and a 50-50 glycol-water blend the boiling point is 265F, operating temperatures up to 230 are normal in severe conditions and still provide 35 degrees boilover margin. Back in the day and to this day PG with AC did not suffer from extreme overheating, so I think you should give it another shot before you install an electric fan.

Most of your configuration appears to be OE and relatively new, but double check everything, again. I think it's also been mentioned that water pump impellers can corrode reducing their efficiency, and there are multiple impeller designs, so disassembling the water pump and checking the impeller condition would be a good idea.

Duke

[Jim D.]

Re: 12V for electric auxiliary cooling fan

lower and upper hoses new from L.I. Corvette and the lower one does have the spring/wire winding inside it.

I think Duke is on the right track looking at your timing and vacuum advance.

P.S. There is no need for a spring in the lower radiator hose. It was only used for the initial fill at the factory.