[1QuickS]

Double check that dizzy advances and returns to initial setting easily. Remove dizzy cap and manually actuate advance of rotor to see if it moves freely. Check idle timing while you are at it. Failure to return to idle, if the above are satisfied would then be rich idle mixture. Check fuel delivery pressure is 3.5 plus/minus 0.5 psi with engine running. Check to see that idle stop screws are 3/4 to 1 turn open from throttles closed and idle mixture screws are 1 3/4 turn open from closed as a starting point. Also (this is important to be sure of) early (1968 and earlier Webers) did not use o-rings on the idle jet carrier screws and later bodies did use an o-ring. If you use the "later" idle jet carriers in earlier bodies then the idle fuel jets WILL NOT SEAT and will allow excess fuel to be delivered to idle mixture screws causing a rich idle mixture which in turn will result in slow to return to idle speed and/or high air flow at idle. If you do not have a STE air flow synchrometer then get one. It will indicate an air flow at idle that will be around 5.5 to 6.0 thereby indicating throttle valves are properly set to idling position and you should then be able to achieve Lean Best idle mixture.

Adjusting floats to OEM geometry per the drawing I sent to you will result in a float needle valve shim thickness of around 0.070 inch plus/minus 0.010 inch. Peening the back side of the tab where the float needle valve rests is important to re-establish a virgin interface with the needle valve.

Many details to attend to but none are difficult, just exacting.

Regarding float needle valve testing: I wet pressure-checked 200 needle valves for PMO and saw 8% failure and the next batch of 200 I saw 1% failure so Richard & I agreed to call them OK for now. He is considering manufacturing needle valves of my design that utilize Viton-tipped needles (as sourced from Holley carbs) and are infinitely adjustable like setting valves on your engine.