John: The carb is now being inspected by qualified personnel. So, lets see what they find. I will tell you as soon as I have news about it. Thank you for all of the technical data and test procedures. We will consider everything before next flight.
Best Regards Daniel ________________________________ From: John Cooper <[email protected]> To: Daniel Arditi <[email protected]>; [email protected] Sent: Tuesday, April 21, 2009 2:02:38 PM Subject: RE: [ercoupe-tech] RPM Drop during Climb Out Daniel: The Stromberg carb is designed for 1/2 psi pressure on the needle valve. This equates to about a 22” column of fuel. That said, I’m certain there are plenty of installations where this is not met. However, to be certified the plane must be shown to provide adequate fuel flow under all normal flight attitudes including maximum angle of climb, so, if this is your problem, something else is contributing to it. A reasonable test can be performed by disconnecting the gascolator from the carburetor, supporting it at the same level it is normally installed, weighting the tail down and turning the fuel on. Catch the outflow in a can or bucket. If you get more than 12 gallons per hour flow rate, this is not your problem. The restriction referred to in a previous message is the measured opening (stroke) of the carburetor needle on its seat. If the needle cannot open the required .048” the fuel flow to the float bowl will be restricted. There are some needles that have a neoprene tip. These needles are not suitable for today’s fuels and should be removed from service as they can swell, the effect of which is to artificially lower the level of the fuel in the float chamber and also restrict the flow. Additionally, the Stromberg design can trap water in the bottom of the float bowl below the level of the jet. This water may get into the jet at extreme climb attitudes or under turbulent conditions or when there is a sudden attitude change, as when you rotate for lift off. Draining the float bowl will not remove this water. The carburetor needs to be disassembled to be certain. John Cooper Skyport Services www.skyportservices.net ________________________________
