The previous owner confirmed that the engine has been reworked to lower the compression and it runs beautifully on 11x6 prop with RPM lower than 9,000.
I am staying with my launch RPM ( 8,850 - 8,900) and 11x6 Brodak prop for a while trying to solve the issues I have mentioned before.
Lowering the tank is no problem but, at this moment, the crest of the tank wedged face is exactly at the spray bar level (the engine has customized venturi with OS 20-40 needle NVA, OS PN# 22311000). Having in mind that the engine runs richer when flying inverted, the fuel pick tube may be shifted w/r to the crest of the wedged face of the tank. I have not seen the area of the tank where the uniflow and fuel pick tubes meet while modifying the tank. This corner was covered with small piece of perforated sheet metal that served as support for both tubes. It is possible that the end of the fuel pick up tube is shifted w/r to the crest of the wedged face of the tank but the only way for me to verify it is to open the tank. Perhaps I will do it but for now I will shim the aft of the tank that, at this moment, sits flat on the fuselage.
What about the engine stopping mid-air in the second flight with some fuel still left in the tank? This happened after a very tight loop and sudden, jerk like correction I was forced to apply. Perhaps this jerk caused the remaining 1 fl. oz of fuel to be thrown somewhere and the engine simply sucked air? How to prevent it? Should I subdivide the tank or maybe use a clunker style? I am attaching the photo of double wedged face of my 7 fl.oz. tank.
Turbulence issue: I added two large wing tips that decrease the wing tip vortices. The amount of this decrease is of course unknown but some decrease must be there. The wings area with flaps went up from 700 to 762 sq. in. Otherwise, there is not much that can be done with aerodynamics of this plane and I know I have to be careful flying in no wind conditions.
Thanks,
M