Dicecal

Living in Phoenix has it's challenges with the heat! I'd like to keep my orginal fan/clutch, which does a good job most of the time. 1965 Coupe, 327/350HP. However, the cooling system gets overwhelmed in the summer heat in stop and go traffic. Will a 7 blade fan do much to improve things? Don't want to go to electric fans or a al flex fan. Want something that will still look basically stock. Which 7 blade fan would be best (part #) Thanks for your advice!

wmf62

i (personally) think you're making a BIG mistake not to try a 7-blade flex fan... you NEVER have to worry about a fan clutch failure with a solid hub.
Bill

John McGraw

The only downside of the 7 blade fan is the noise! We pulled a 5 blade asymetrical fan off of a friend's 67 coupe and replaced it with a 7 blade and he could not stand the fan noise. This is from a guy who has side pipes!
He ended up putting an electric fan on the car.

The standard 5-blade fan should get the job done if the radiator is good, and if not, the 7 blade fan is a short term fix. There is a reason that GM used the asymetrical 5 blade design, and the reason was noise.



Regards, John McGraw

Dicecal

Everything is new and tested in the cooling system. 110-120 degree heat with no humidity, the stock system gets taxed in stop and go traffic. I realize I may have to live with some nosie for cooler temps, was just wondering how much better cooling there may be with a 7 blade fan.

toddalin

Is the shroud thouroughly sealed around its perimeter? Makes a big difference, especially at idle.

Personally, I run a 7-blade flex fan (no fan clutch) on the '64.

wmf62

John
my 7-blade is asymetrical and is relatively quiet. the 6-blade i used previously was symetrical and not objectionable.

i guess beauty is in the eyes, and also the ears...



whatever one uses, make sure it is a quality product....

Bill

savewave

I had a 7-blade asymetrical on my '65 BB when I bought it, but switched to stock with a fan clutch and saw no difference in operating temperatures.

When I added Vintage Air, I had an electric fan added in front of the radiator. I've seen the temperature gauge hit the vicinity of 210 several times in traffic, but it's never boiled over.

Plasticman

You make the point that you do not want to use an "alum. flex fan".

I agree completely, but don't discount a quality 7 blade asymetrical stainless steel bladed flex fan for max idle air movement, with a minimum of noise increase (if any), as Bill indicated for high ambient operating conditions.

However, it would be wise to ensure that the rest of the system is up to "snuff" as well (as other have pointed out).

If my 62 (350 powered with headers) ever gets to 195 (and the gauge is accurate as verified several times with an infared "gun"), while operating in the Florida summers at idle, I would know something is very wrong.

And this is with a stock water pump and water pump pulley #3900434 (63-65 Vette dual belt). Water pump pulley measures about 7.125"" and the crank pulley #3744043 (63-66 Vette dual belt) measures 6.625", and they clear each other by about 1/16". I run 2 belts. One for the crank, water pump, & alternator. The other goes to just the crank and water pump (easy to install once the correct length belt is found, by removing the water pump pulley, install belt with pulley on an angle, and bringing it vertical onto the pump flange).

Also note that I am running an old aftermarket copper/brass radiator!

Plasticman

avideo

and it keeps the engine cool even in 95+ degree temperatures in August at Hot August Nights. I can even let it idle on a hot day for an hour plus and the temps never go over 200 degrees. I might add my car has factory AC; and AC C2s are well known for running hot. Keep in mind that a flex fan will typiically move more air at idle than a stock fan will. Keep that in mind.

Dicecal

Thanks for the replies. Flex-a-lite makes a 7 blade asymetrical..maybe I'll try that. Just wanted to keep the engine compartment as "stock" apearing as possible. I have gone thru the entire cooling system, and tried many different fan clutches.

Plasticman

The Flex-a-Lite looks appropriate. We use to get GM flex fans from the junk yards for a song (used on the big GM AC cooled passenger cars and station wagons of the 70's and early 80's).

Don't forget that you will need a suitable length spacer to position the fan blades 1/2 in and 1/2 out of the shroud, and then bolts to match.

Good luck,
Plasticman

salty_waders

This can make a difference.

toms silver 60

Bill talked me into buying a used 7 blade flex fan at Old Town, and it has performed very well. A new aluminum Griffin radiator helped a lot, but the different fan clinched it. Car has since spent a lot of idle time in the driveway getting the tri power dialed in and never had a hint of overheating. And this is with the two lower fan shroud pieces not installed for access reasons. Temp gauge used to start rising at every light.
Running built 350, lots of cam, vac adv distributor, 3X2 carbs.

Powershift

I have a 1967 with 327/350 HP and factory AC. Have a stock GM (Eaton) fan clutch with 7 blade GM fan #3931002. Cools very well with no significant fan noise. And that includes summertime here in south Louisiana.

Paragon used to sell these GM 7 blade fans....and may still have them. Call and check.

Not sure if you have air conditioning or not? However, the mid-year Corvettes with factory air had a lower radiator shroud extention and additional weatherstripping around the radiator area for better air flow through the radiator and engine cooling.

Consider installing these if you do not already have.

Larry

obx2323

I run a 7 blade Flexalite stainless direct drive fan on my '65 w/350 built to 400HP with a stock 5 year old rad. under 70 degrees I have to slip a piece of cardboard to make it run 160. It also keeps the cockpit a little cooler as it is pumping air through the gills IMO. NO EXTRA NOISE. I bought mine from Summit. That's with a 180 degree thermo. I also put a 7qt oil pan as I was really worried on having an overheating issue when I got the car last year and started restoring/adding HP. Over engineered the cooling capacity I guess, LOL.

Oriondriver

How do you do it? I have tried everything to get mine to run on temp... and I continue to battle with it...

Scott

Kensmith

I also have the Flex-a-lite 7 blade stainless flex fan. Not noisy at all and does a great job cooling. I live in the Sacramento Valley with temps in the 110* range and run Vintage A/C.

383 stroker motor, 450hp 450tq, 10.5 compression. DeWitts aluminum radiator.

toms silver 60

Believe the answer is plenty of air flow at idle. I tried a 17 inch steel racing fan right after the 350 was installed, it helped idle temps a lot but it was noisy at hiway rpm and ate up a bunch of HP. Thorough block flushing and draining is a minimum, make sure you get crud out of block. I run vacuum gauge to make sure I have enough inches to actuate the low vacuum can on distributor (yes, vacuum advance helps). Also, idling on rich side helps as well as does not having any vacuum leaks. No fan clutch for sure, one more thing to go wrong. Another thing, make sure your fan belt does not slip; I took a trip to Frank's and Mike's places the other day and temps were a little higher than normal. Found out my single fan belt was slipping.
I was very pleased to see engine temp on the low side after idling for extended periods as I was setting up tri power linkage.
Another thing, fan is not noisy.

Avispa

Seems Paragon Reproductions no longer sells replacement 7 blade clutch type fan blades. A stock appearing replacement 7 blade fan can be found here if you really want to keep the stock fan clutch and stock appearance.


http://www.corvetteparts.com/details/iid/13668701.htm

AZDoug

I have a 7 blade GM fan off of a '69 Z28 (IIRC) I think he said they were used on LS6 Chevelles, also, that I got from Vetrod62.

It is attached to a Hayden fan clutch. I have never heard the fan clutch lock up, so nothing is getting to 210 F.

This is on my 427 small block motor.

I like the fan clutch for the same reason i like light weight flywheels, less drag on the motor during acceleration

Doug