I have recently swapped out a tired Zenith for a good one on my 63 wagon. It has transformed the car. I am now looking at re-building the original Zenith so that I can swap them again when I get my other 63 back on the road. I have noticed some distortion on the carb body that strikes me as a bit un-usual.

Firstly the two faces that the float chamber mate to are not perpendicular. When I offer up the float chamber with the horizontal join tight, there is about a 10 thou gap at the bottom edge of the vertical joint. Aside from this joint not being clamped up with any screws, having these faces not mating correctly certainly won't help that gasket to seal.

The second fault is on the flange that bolts to the inlet manifold. The hole at the bottom face is 66 thou out of round. It is longer in line with the axis of the throttle flap and shorter across the line of the mounting holes. I am guessing that this would have originally been circular and that it has gone out of round due to over-tightening of the mounting nuts.

The other deflection that is noticable is at the top rim of the air intake. The edge is bent inwards at the front left quadrant. I suspect this coincides with the orientation of the clamp that holds the hose coming from the air cleaner - and that this clamp has been over-tightened.

Has anyone else discovered these problems with an aged Zenith? I am picking that the first issue was a manufacturing fault and that the second and third are from abuse during assembly or servicing. The venturi body is quite a loose fit in the barrel of the carb as well. I might shim this to prevent it rattling around.

Anyone have any words of wisdom about rebuilding these things? I am not interested in replacing them with anything different at this stage.