Mentor 140 Problem

[Robert Schofield]

I need advice. I have been trying to dial in a Mentor 140 for 6 or 7 months. I have about 7 or 8 gallons of fuel thru it. It took forever to get it to run half way right but it finally started to work. I have it in a test plane because I still don't trust it. After break-in I tried to fly it but it would surge at any low power setting. The people I got it from sent me a new pump and carb. It will now idle well but mid-rang is so rich it will 4 stroke. I was told to lengthen the pipe, which I did. It was set at 1/2 in. between the header and front of the pipe. By the way the pipe is the aluminum pipe from Mentor. The header is a 30mm. rise from Mentor. 
I leaned the low end and set the pipe at 3/4 in. spacing. I also leaned the top end. I have tried lean and rich on both top and bottom. It always runs very rich mid-range. I am using 15 % Cool Power. 17x8N APC. RPM top is 8800. I richened it to 8400, 8500, 8600. Idle is very good and reliable. When I pull verticle, that is when it leans out and runs like it should, however blowing the top of the box at 80 mph ain't cool.    
I was told to lower the pump pressure, which I have not done yet. 
I have run YS,OS,Supertiger, Hano's for 15 years, but this is the most flustrating thing I have ever seen.
The power is scary, however I would like to have throttle control instead if a "parked and gone" switch. 
HELP
Bob Schofield    
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