The Roundel has mentioned that a problem with the early sixes (in this case, 1970 BMW 2500) is warping of the bottom surface of the carburetor body.
I tried gluing the top surface of the flange gasket to the already warped surface of the carburetor with GE silicone glue. Use as little glue as possible and refit with just a snugging torque. Let the glue set the full suggested time before using the car.
I also found that both sides of the butterfly valve housing were warped as was the manifold surface itself. I trued them up using 380 to 400 grit sandpaper glued to a seven-inch circle of 3/8" glass. This is a miserly solution to an otherwise very expensive repair. I would be glad to discuss it with anyone.
Author: Lynn E. Bjorklund
9342 Hunting Circle, Villa Park, CA 92667
The warping problems don't usually start until the 1972 model year. The original article pointed out some areas of warping and suggested that you were free to find others. Looks like you have. Thanks for the tip. Tech Ed.