Wow, what a difference! No gasoline smell, no run-on, reliable return to idle, nice throttle response, and the car even sounds better.
I have an appointment booked for some dyno time at 11:00am on Saturday March 17th. I'm going to use that to get the carburetor finely tuned, including:
- idle mixture and idle throttle opening
- primary & secondary main jets
- primary power valve vacuum rating and PVCR sizing
- primary & secondary accelerator pump cams
- primary & secondary squirter nozzle sizes
By juggling all this, the end result should be exactly the right amount of fuel and air available for combustion at all times, and a VERY responsive engine. Fuel economy should be improved, too.
Until my dyno day we won't know for sure, but my guess is that 700CFM is quite appropriate for my somewhat upgraded engine. I happen to already have a double pumper, but if I was buying a new Holley I would go for a Street Avenger 770CFM with vacuum secondaries (actually I want quad Webers).
The beauty of the vacuum secondaries is that you can somewhat oversize the carburetor, and not cause problems. If your engine cannot use 770CFM, the secondaries won't open all the way, so the mixture etc. will still be correct. On a mechanical secondary (double pumper) carb, to get that effect you have to convince the driver to lift his foot slightly.
(I'd bet on the vacuum secondaries.)