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Weber Banjo bolts are 1.5mm pitch and different thread pitch from the Zenith and Solex, which are 1.25. The Weber bolt will go in a couple turns but then gets hard and screws up the threads.
So a local 356 guy has a zenith top with bad threads. We drilled out the bad threads and inserted a heli-coil insert into the fitting.. Not too hard and he is back on the road.
Was not too bad except for indexing the carburetor top to drill the old fitting. We set it up on a 90 degree angle plate and indexed off the bottom two screw holes. Then ran a dial indicator up a transfer punch to insure we were square. The set up is not too hard but its is critical. Insure the carb top is not warped and its is flat.
Then set it in the press, indexed off the center of the banjo fitting then bored it out for the insert. We left it locked to the table and re-tapped the hole. We used a spring loaded tap follower to insure it went in true. Then screwed int he heli-coil and it is almost good as new. This will also work for the 5mm top screws but remember they are .8mm pitch, Alignment and set up here is the real trick for getting it correct. A good center finder and spring loaded tap follower will make it almost factory again
Thanks for looking.
So a local 356 guy has a zenith top with bad threads. We drilled out the bad threads and inserted a heli-coil insert into the fitting.. Not too hard and he is back on the road.
Was not too bad except for indexing the carburetor top to drill the old fitting. We set it up on a 90 degree angle plate and indexed off the bottom two screw holes. Then ran a dial indicator up a transfer punch to insure we were square. The set up is not too hard but its is critical. Insure the carb top is not warped and its is flat.
Then set it in the press, indexed off the center of the banjo fitting then bored it out for the insert. We left it locked to the table and re-tapped the hole. We used a spring loaded tap follower to insure it went in true. Then screwed int he heli-coil and it is almost good as new. This will also work for the 5mm top screws but remember they are .8mm pitch, Alignment and set up here is the real trick for getting it correct. A good center finder and spring loaded tap follower will make it almost factory again
Thanks for looking.