Re: newly rebuilt rochester quadrajet woes
You'll hear the secondaries open on a Q-jet, just like Krass & Bernie comics, WA-AA-AA!
This is also a choke lockout on top of the air horn pass side. If choke plate is partially close, this lockout will prevent the air valve from opening up. Check to make sure the exhaust crossover is open under the carb so the divorced choke heats up enough to open the choke, or shorten the choke linkage to adjust the stroke.
Once the choke potential problem is fixed or found to be working correctly, snap carb from idle to WOT and transition to WOT throttle should be smooth. If air valve opens too fast, the engine stumbles; if too slow, engine is lazy. You will not be able to get the secondaries to go completely open sitting in neutral, but you will be able to see/witness the action of the opening secondaries.
As said. you can adjust the the spring controlling the opening point of the airvalve witha 3/32" Allen wrench and a 1/8 inch flat blade screwdriver. Books/papers suggest 1/2-3/4 turn of the spring is correct, but I have found more than full turn is needed. After adjustment, its trial & error on tension; 1 turn almost, another 1/4 turn is better, but still there, etc., etc.
Also, another factor in engine acceleration is timing. You may need to advance initial timing to help.
Good job on acquiring 19" of vacuum - leakfree intake system.
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CUBS - 2016 World Series Champions - maybe this year, 2019 ...