Debra
11-29-2007, 03:52 PM
Evening Clarence,
A few of the flyers at my club are having the same problem as I am. We all have O.S. 48 Four stroke engines that do not run well mounted at 90 degrees.
I have two and neither one runs well in that position. Raising or lowering the tank does not help. The problem is the low end is to rich. Removing the air bleed adjusting screw completely did not help. What can I do other than drilling out the air bleed hole?
Putting a clunk on both lines in the tank helps but long idle time loads up the engine. I am using Wildcat Premium Fuel 10% nitro 18% caster. Also using a Master Airscrew 12-6 prop.
I use the same fuel in all my engines without problems. All my other four stroke engines run well in any position. What do you suggest?
Thanks,
Charles M.
Long time reader of your column
Dear Charles,
Having only run the O.S. 48 in the upright position without any problems it is pretty hard for me to say why the engine should not perform well when mounted horizontally. Although you raised and lowered the tank, you didn't say where the centerline of your fuel tank is in relation to the carburetor intake. The centerline of the tank should be even with or about 1/4" lower than the venturi. If higher, you can expect loading. If your tank position is okay, then drilling out the air-bleed or notching the top edge of the carburetor barrel is the only answer.
Yours,
Clarence Lee
A few of the flyers at my club are having the same problem as I am. We all have O.S. 48 Four stroke engines that do not run well mounted at 90 degrees.
I have two and neither one runs well in that position. Raising or lowering the tank does not help. The problem is the low end is to rich. Removing the air bleed adjusting screw completely did not help. What can I do other than drilling out the air bleed hole?
Putting a clunk on both lines in the tank helps but long idle time loads up the engine. I am using Wildcat Premium Fuel 10% nitro 18% caster. Also using a Master Airscrew 12-6 prop.
I use the same fuel in all my engines without problems. All my other four stroke engines run well in any position. What do you suggest?
Thanks,
Charles M.
Long time reader of your column
Dear Charles,
Having only run the O.S. 48 in the upright position without any problems it is pretty hard for me to say why the engine should not perform well when mounted horizontally. Although you raised and lowered the tank, you didn't say where the centerline of your fuel tank is in relation to the carburetor intake. The centerline of the tank should be even with or about 1/4" lower than the venturi. If higher, you can expect loading. If your tank position is okay, then drilling out the air-bleed or notching the top edge of the carburetor barrel is the only answer.
Yours,
Clarence Lee