re Fan Blade

[Wayne P.]

Would it be advisable to go with a seven blade over my 5 blade to give additional cooling when sitting in traffic ? I assume this was done for air-conditioned cars. I had the engine re done and I believe the work done
on the heads has caused the engine to run hotter. 327 365 solid lifter rollers. 190 on highway . sitting creeps up to 225. Thermostat 185 Mr gasket high flow. 65 % antifreeze . I am using a bought temp gauge with sensor in intake to make sure of accurate reading. My oil is Brad Penn 20w-50
Timing good runs great .
Thanks for any advice.

[David L.]

Re: re Fan Blade

I have been using a 1968 Chevrolet passenger car w/AC 7-blade 18" dia. fan w/aluminum blades (GM # 3931002) in my 1966 Corvette instead of it's original 17 1/8" 5-blade fan (GM #3770529). It has to run cooler. The 3931002 fan was a one year deal (1968 only) on passenger cars only, not 1968 Corvettes. The 3931002 fan also serves as a replacement for the 66-67 Corvette w/AC 5-blade 18" dia. fans (GM #3789562 and GM # 3863137). If you need a 3931002 fan I believe that I have an extra one in my collection that you can have for cheap money.

[Jack H.]

Re: re Fan Blade

In '64, we look for 7-blade fans on A/C equipped cars and the standard, base, 5-blade fan on non-A/C cars. If you're convinced of the accuracy of your coolant temp gauge and feel your engine is running hotter than 'normal', you have several alternatives.

(1) Yes, you can install a 7-blade fan to push more air through the radiator, but ask yourself 'why' you need to do this? Factory original non-A/C equipped cars didn't need a 7-blade fan, so are you simply putting a 'bandage' over other problem(s)????

(2) The car was factory equipped with a Harrison aluminum radiator. These have a DEFINITE useful service life before internal corrosion begins to diminsh the radiator's cooling efficiency...

(3) The fan was equipped with a fan clutch that was BOTH temperature and RPM sensitive to generate as required 'slip' between the driving hub on the water pump and the fan itself. If the fan clutch isn't in proper working condition, you could be losing air flow efficiency that would FIRST show up at idle/low speeds where the fan IS the primary driver for forced convection air flow through the radiator...

[John H.]

Re: re Fan Blade

65 % antifreeze . I am using a bought temp gauge with sensor in intake to make sure of accurate reading.

Wayne -

The normal anti-freeze concentration is 50-50, and water is a better coolant (in terms of heat transfer efficiency) than anti-freeze; is there a reason you mixed the anti-freeze at 65%? Have you verified the accuracy of the temp gauge with an I.R. gun?

[Wayne P.]

Re: re Fan Blade

Temp is correct . I will re check antifreeze. Thanks