1940 6 blade fan
- Thread starter gearheadbill
- Start date
gearheadbill
Senior Member
Weren't most factory fans 4 bladed?
deuce_roadster
Well-known member
Every 39 deluxe-40 V8 fan I have seen had 6 blades.
gearheadbill
Senior Member
Good to know...thanks
Hal Beatty
Senior Member
Yeah, that's a stock fan for a '40 Deluxe. Mine has the same thing...
Probably more for sound reduction. The vortex from the leading blade tip will cause a pop when the next passes through it if they're the same size.
Lonnie
gearheadbill
Senior Member
Again, good to know. Thanks guys!
drolston
Well-known member
Advice for all fixers of crank mounted fan vehicles (39 - 41):
Before installing your fan, do a quick check by laying the fan face down on a flat table and see if all of the leading edges are touching the table. Then set it on the hub and check the that all of the trailing edges are the same height all across the length of all of the blades. Same thing for all of the leading edges. I installed a NOS six blade on my '41 without checking, and picked up a small but annoying vibration. Felt like the engine rotating assembly was out of balance. Drove the car without the fan and the vibration was gone. Adjusted the blades to level them out and all is smooth. The tip of one blade was about 1/2" low; another 1/4".
I put a crow bar in the center for leverage and was able to bend the blades up or down by hand, a little at a time.
Those fan blades bend easier than you might think. I will never again turn over the engine by pulling on the fan blades.
Before installing your fan, do a quick check by laying the fan face down on a flat table and see if all of the leading edges are touching the table. Then set it on the hub and check the that all of the trailing edges are the same height all across the length of all of the blades. Same thing for all of the leading edges. I installed a NOS six blade on my '41 without checking, and picked up a small but annoying vibration. Felt like the engine rotating assembly was out of balance. Drove the car without the fan and the vibration was gone. Adjusted the blades to level them out and all is smooth. The tip of one blade was about 1/2" low; another 1/4".
I put a crow bar in the center for leverage and was able to bend the blades up or down by hand, a little at a time.
Those fan blades bend easier than you might think. I will never again turn over the engine by pulling on the fan blades.
mrtexas
Well-known member
Likely set up that way so the fan doesn't get harmonic vibrations. With the blades spread evenly and the same length there is the possibility to get vibrations that get bigger and bigger that could break off the blades. If you look at the blades of a late model car they can be even more un-even to prevent the destructive vibrations. The analogy is pushing a kid on a swing. If you push at just the right time the kid goes higher and higher.