Venturi opening
02-20-2003, 01:53 PM
#1
Venturi opening
Bob, In your instruction you mention reducing the opening of the barrel of the carb to reduce the effective choke area as the diesel really does not need all that area needed for glow. You mention reducing this to about 80% but is this a hard and fast number. In choosing several prop loads we found that different choke areas enhanced the performance of the motor. Have you ever done any work on this and do you have any optimums/minimums for general engine classes. Thanks Dennis
02-20-2003, 02:25 PM
#2
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Venturi opening
What were saying is that with a typically recommended propeller most engines will max out there performance at about 80% carb. opening. Since we wrote the directions to cover all engines its only a guide line.
For example a 40 la has a carb as big as a typical .25 thus you might need 100% open. As we say in the direction the final opening will be were ever the engine max's out. The general rule is your tachometer is your guide, if you get more power by opening the carburetor then take it.
P.S. when we were doing our work on ducted fan we found we needed 100% open all the time what this told us is that most ducted fan engines were undercarburated.
For example a 40 la has a carb as big as a typical .25 thus you might need 100% open. As we say in the direction the final opening will be were ever the engine max's out. The general rule is your tachometer is your guide, if you get more power by opening the carburetor then take it.
P.S. when we were doing our work on ducted fan we found we needed 100% open all the time what this told us is that most ducted fan engines were undercarburated.
