1967 cooling fan

[Jerry W.]

I have a 1967 327 350HP air car, I live in Gilbert, AZ where it gets hot and would like recommendations on the fan to use. I understand that a 5 blade 34 degree fan was the standard, although I have an original GM parts book that calls out the use of a 7 blade fan for 64 through 67 327 air cars. I would like to know if a 5 blade 34 degree will move as much air as a 7 blade, both being 18 inch blades. Long Island now carries all these blades as well as clutches. I currently have a standard 5 blade 25 degree blade and a old clutch which doesn't cut it. I want to replace both. Regards Jerry

[Jack H.]

Re: 1967 cooling fan

Give us a few more words on what you mean by "doesn't cut it."

For example, how frequently does your rad cap pop, you gush coolant all over the engine compartment and have to have the car towed home. Or, are you simply seeing higher readings on your dash temp gauge then you're comfortable with...

[Kim C.]

Re: 1967 cooling fan

you can also use the clutch eliminator (lic #24-30r)
this makes it spin continuously giving more cooling

[Joe L.]

Re: 1967 cooling fan

you can also use the clutch eliminator (lic #24-30r)
this makes it spin continuously giving more cooling

Kim------


Definitely! No fan clutch ever made will provide better cooling than eliminating the fan clutch altogether. That's the "ultimate solution" as far as maximizing the ability of the fan to draw air.

If, after eliminating the fan clutch, someone wants to get even more out of the fan, install a smaller waterpump pulley.

[Joe L.]

Re: 1967 cooling fan

I have a 1967 327 350HP air car, I live in Gilbert, AZ where it gets hot and would like recommendations on the fan to use. I understand that a 5 blade 34 degree fan was the standard, although I have an original GM parts book that calls out the use of a 7 blade fan for 64 through 67 327 air cars. I would like to know if a 5 blade 34 degree will move as much air as a 7 blade, both being 18 inch blades. Long Island now carries all these blades as well as clutches. I currently have a standard 5 blade 25 degree blade and a old clutch which doesn't cut it. I want to replace both. Regards Jerry

Jerry------


I don't think you'll find any significant difference in going from the 5 blade fan you have to the 7 blade.

Many years ago I changed the 34 degree, 5 blade original fan in my 1969 to the 7 blade GM #3955182. If it made any difference in cooling performance it wasn't enough to be noticeable.

[David L.]

Re: 1967 cooling fan

Jerry,

The base fan wo/AC (GM # 3770529) is 5-blade 17 1/8" dia. with a 1 5/8" pitch.
The 66-67 AC fan is 5-blade 18" dia. with a 2 1/4" pitch (GM # 3789562 made by Hayes-Albion or GM # 3863137 made by Schwitzer and stamped 912239 with a date code).

sin 34 degrees X 4" = 2.24" = pitch

I have a 1966 300HP wo/AC and I use a 7-blade 18" dia. fan with aluminum blades (curved tips) stamped 3931002 and a date code. The 3931002 fan was a production fan for 1968 Chevrolet models w/AC only but NOT Corvettes. Even in the summer in southern NH on days that are in the 90's I believe that the my engine seems to run too hot.

Dave

[John H.]

Re: 1967 cooling fan

I have a 1967 327 350HP air car, I live in Gilbert, AZ where it gets hot and would like recommendations on the fan to use. I understand that a 5 blade 34 degree fan was the standard, although I have an original GM parts book that calls out the use of a 7 blade fan for 64 through 67 327 air cars. I would like to know if a 5 blade 34 degree will move as much air as a 7 blade, both being 18 inch blades. Long Island now carries all these blades as well as clutches. I currently have a standard 5 blade 25 degree blade and a old clutch which doesn't cut it. I want to replace both. Regards Jerry

Jerry -

Assuming that you have the correct Harrison stacked-plate aluminum radiator (not a look-alike copper/brass replacement), and the stock top-of-radiator support-to-hood seal, you can improve your idle and low-speed traffic cooling airflow by sealing the radiator to the radiator support and the fan shroud to the radiator; black foam pipe insulation is relatively unobtrusive and easy to install. This forces all the air through the radiator instead of losing airflow around or over it.

If you have cooling issues at normal highway speed where airflow isn't an issue, look to the radiator as the culprit.