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Engine/PSRU direction of rotation

Posted: Fri Feb 17, 2012 9:22 pm
by Mike Kimball
I read here (http://www.melling.com/marine_rotation.htm) that a "Standard"
engine crank rotates counter-clockwise when viewed from the flywheel end and
a "Reverse" engine is the opposite. Does anyone know if, generally, helical
geared prop reduction units maintain the direction of rotation of the engine
or does the reduction unit reverse the direction? I want to use a standard
three bladed prop, so I need to know if I should order a Standard direction
Chevy or a Reverse direction. I'm getting pretty close to completing the
basic airframe so I am getting that much closer to ordering an engine. The
Dart Aluminum Block Chevy 350 looks like the one for me. Next I have to
figure out whether I want 23 degree heads, or 18 degree heads, cam grind,
and stuff like that. Sure wish I knew something about that stuff. I think
I can just tell a performance shop that I want max RPM at 4500 and max
continuous RPM at 3375 and that I want it to idle smoothly at 600 RPM and
they can set me up with the correct lift and dwell on the cam. 600 RPM
idle. Hmmm. That would put the prop at 359 RPM with a 1.67:1. That'll
probably seem kinda weird. What'll look even weirder will be the glass-pak
mufflers and chrome exhaust pipes going all the way to the back of the
plane. Seriously, does anyone ever put mufflers on airplanes? Seems like
prop and wind noise contributes the most to the cockpit environment, so
probably not.

Mike Kimball
SR #044




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