Here’s a new manifold I have been playing with, using an IDF Downdraft Weber. In a back to back comparison with a 45mm Sidedraft Weber and a fully ported short Redline manifold, it was 5-7Ft/lb of torque better across the board from 3-6500RPM.
The 45mm wouldn’t take full throttle below 3500 revs. Where as the downdraft would go down to 2500 revs. The beauty of this setup is you don’t have fuel blowing back in your face through the speedo hole, and hopefully doing away with the fuel smells you get with the sidedrafts. And yes, it does clear the bonnet and you can get a thin air filter on it too… Just.
This will be one of the manifolds that will be used on the new small bore project motor on the dyno. Keep checking back!