Again with the semi-failure

Post date: Aug 15, 2012 3:40:05 PM

Good news: Tank is done! Epoxied on a 16ga ring using Marine Tex which seals nicely to the flimsy pan, is gas resistant, and provides a solid seal surface for the pump lid. Glad to have that project behind me. It's ugly as all get-out, but works. Total cost was just the fuel pump, $40 for the tank sealer, and about $20 in scrap metal, baking pan, and the drain plug. Somewhere around 60 hours of labor, though. Hm.

Did another test run, this time with very large air bypass (0.120) and a lighter piston spring. Still lots of problems idling. It did get to the point of idling without primary drip, but still wasn't very happy. Tried smaller bypass (0.095) but went back to worse. Idle screws have very little impact, seems to be running very lean. Seemed to be an air leak between the base of the carb and the intake. Take it off, and the base of the carb seems warped by about 0.006"! Fully tear down the base plate, and it's perfectly flat! I can only assume I gorilla-tightened the base plate screws so much that they warped the plate. So, hopefully another try this weekend. Normally it takes some heft to get that base to fuel bowl gasket to seal, but maybe not this particular type.

Also learned something new. I had horrible air leaks after building the carb with the Ruggles HP rebuild kit. Turns out they gave me the wrong base to bowl gasket. Only a very slight change in the location of one hole, but that opened up something!

In other carb news, I got the APT screw out and the "external APT screw" from Ruggles. They just take a normal air horn screw, turn it down to be smooth on the end and throw on a spring. At least it was only $3. Also drilled out and tapped the air bypass holes for 1/4" set screws so I can easily change bypass air sizes.