| [GMCnet] Must have been a nightmare cooling these FMCs [message #283199] |
Sun, 26 July 2015 10:35  |
glwgmc
Messages: 1014
Registered: June 2004
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I stumbled on this about trying to cool the FMC motorhomes. They were contemporary to our GMCs but used a rear mounted, rear facing Chrysler 440 with a rear mounted radiator. From the sound of it whether trying to pull air in through the radiator with a fan or trying to push air out through the radiator with a fan was at best a difficult proposition! Makes our discussions about cooling our GMCs sound easy….
From a FMC chat group posting:
"If you want to stay with a "push" into the shroud setup (tries to cool 230 deg radiator water with 300 deg + air heated by the exhaust manifolds) then you want what is called a "reverse rotation fan".
Fan blades are curved or cupped (just like a "spoon") that "scoops" the air across the blade. That curve or cup has to be in the direction of rotation. Just as you can't scoop a spoonful of water with the back side of a spoon, a fan blade curved away from the direction of rotation does not move much air and just makes a lot of noise. This blade curvature, direction of rotation, and which way it is mounted are important. There has been more than one FMC reverse rotation pusher fan installed BACKWARDS.
When doing anything with the FMC fan . . . remember . . . looking in the street side engine bay door, the top fan blade rotates TOWARD YOU. If you HAVE A PUSHER FAN, that top fan blade "scoop" should be rotating toward you as a cup or curve. Look at it and study which way the blade is curved and convince yourself that the "scoop" is facing the right way toward the radiator (for a PUSHER) on that top blade that will rotate toward you. Of course, if you have a SUCK fan (takes in ambient temp outside air that flows thru the radiator, then shroud, then thru the fan that BLOWS the air ON the exhaust manifolds, then out the sides and bottom) the blade curve is reversed. Rotation is the same, but the blade curvature is the other way. Fans are made one or the other, and are not reversible by just turning the whole thing around.The fan blade should be ABOUT half in and half out."
Jerry
Jerry & Sharon Work
Kerby, OR
glwork@mac.com
http://jerrywork.com
78 Royale with most everything done to modernize a GMC mechanically
77/94 Clasco bone stock and looks like it just left the Clasco facility
Both drive equally as well.
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Jerry & Sharon Work
78 Royale
Kerby, OR
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