You put the nails in your coffin when you tightened down that carb. You warped the air horn and caused the secondaries to malfunction. That is a moot point now. The solex which is basically an American Quadro Jet was, in my opinion, a piece of garbage. I would highly recommend the conversion to Webber. The only time I would disagree to a conversion would involve Zeniths. These carbs from the 60s and 70s are not well understand. People who say to get rid of them don't know how to set them up. Another impressive carb is the Stromberg 175 CD. It's the closest a carb will ever get to fuel injection, but unfortanately it is restricted to smaller engines.
Auto Zentral Ltd.