[burnin oil]

That doesn't surprise me in the least. When you have a broke carb or none at all, a carb that is 95% tuned is definatly an improvement over what you had. The carb is really only allowing a certain amount of gas in with a given amount of air. It really doesn't care if it's a 305 or 454 since we set the initial throttle opening. Most stock engines perform in the same way as far as actual airflow requirements go so the carb keeps the mix going either way. Most tuning envolves correcting AFR via the jets and experienced tuners will try and adjust the timing of the individual circuits. Carbs are stupid simple but terribly irritable. Long story short all a rebuild has to do is make sure the jets are slightly rich along with the accelerator pump and the carb will perform well enough on several engines. Add in the qjets air door mechanical secondaries and it's almost impossible to over carb an engine.