7 blade fan
 

As you may have read in my build post I don’t have an overheating problem per se but I do have a little bit of temp creep in hot weather. Looking at winter projects and things to ask for for Christmas and one of the things I came across is the 7 Blade 18 inch fan Ames sells. I have the 6 blade Derale now but one of the Facebook Pontiac groups I am a member of says the 7 blade is indeed superior. What’s the concensus on this? I don’t need but a tiny bump in air flow to stop my temp creep. Anyone got any insight?

All the factory clutch fans I run are all of the 7 blade variety.

Use the largest diameter fan that will fit into your fan shroud.
 

The best of the factory fans were 19 1/2" in diameter.

1970 version is part number 9796134. I think there were two more versions later into the 1970s, but don't know the part numbers.

I can’t fit a 19 inch fan in my shroud but thank you.

If the 19 1/2" won't fit, use the largest 7-blade fan that will fit.
 

An 18" 7-blade should still move a LOT of air.

https://www.jegs.com/i/OER/691/K193/10002/-1

They move enough to cool 800hp 600 cube engines :)

Do you happen to know if this one will bolt to a Hayden severe duty clutch

Factory shroud? I would think about getting a bigger shroud if possible.

It shows as a replacement for the factory GM clutch-fan blade.
 

They show it fitting GM vehicles from 1967 to 1979, so it would work with the replacement clutches (like the Hayden variety).

Good luck!

I have the biggest shroud that will fit my core support and radiator

This is from m '64 GTO. I made a custom shroud. So it is possible to have a 19" fan.

https://forums.maxperformanceinc.com...1&d=1728652818

I’ve used these fans in the past with good success. They’re heavier duty than most of the aftermarket stuff. You can usually find them in different diameters. HTH


https://www.ebay.com/itm/28605910149...Bk9SR6SmzL7PZA

Yeah I have a stock pile of those. They are gm units with a part number.

Probably the best working fan on the planet, they pull a ton of air. Also great when you don't have room for a clutch

I stopped using them however when I started searching for HP, they are big hp suckers. I switched to clutch fans on the cars that I could. I still run 2 of those on cars with no room for a clutch.

Your fabrication skills are much better than mine but if its not too expensive I would be willing to pay you to build me one

One source....

"A fan shroud should fit the radiator, and there should be some clearance between the two. The shroud should be measured to the radiator to determine the correct size.
At least 1 inch of clearance between the fan shroud and the radiator."

Another source:

https://www.motortrend.com/how-to/bu...-a-fan-shroud/


.

Well, maybe not. I've done two conversions on friends' cars where we used the 19.5" fan and the big shroud on 15-1/2" radiators. Just takes making a hole through the large shroud for the bottom radiator hose.

The shroud bolts up to and locates on the radiator support so it remains centered with the fan. The top of both the short and long cores is in the same place so the only difference is at the very bottom.

It's been awhile but believe this shroud was from OPGI and the Ames shroud fits better up to the radiator.

Thanks lust4speed. I think this is exactly what I’m gonna do in the spring. Did you use the clutch fan from Ames?

The 7-blade 19.5" fan came from a pick-a-part and the fan clutch is a 2797 severe duty from O'Reily. I don't think anyone carries a new 7-blade 19.5" fan similar to the original equipment fan.

What vehicles should I be looking for to get the 19.5 inch fan

Any Pontiac or Oldsmobile with AC from about 65 to 72, but the list could be longer. Maybe someone can fine tune the cars to look for. They come up on eBay all the time but you do need to look over the pictures and make sure none of the blades are damaged. Also don't believe descriptions since sellers either don't know or don't care about accurate descriptions. That's one good thing about scrounging the yards is you get to see the fan first hand. There are always two opposing blades and the tape will definitely show 19.5" from tip to tip between those two. If the measurement comes up at 19" (or less) then it didn't come from a Pontiac/Oldsmobile air car.