[Cliff R]

"may be a stupid question, but here goes, on the later model 77-78, carbs, would there be any improvement by cutting off the choke horn and blending/radiusing the air entry there?"

Not sure as I've never removed one.

I've also done some testing with and without the choke flap and shaft installed and saw NOTHING, at least at my power level (well over 500hp and near 600ft lbs torque). I also supply a LOT of racing carburetors, pure stock FAST, and have done a number of truck pulling carbs (well known for that deal), and some Stock and Super Stock units. We've acheived some excellent results with the Q-jets and never touched them anyplace with a grinder or sanding roll. No "thinning" shafts or "knife edging" throttle plates, etc.

The two biggest gains I've seen in power are optimizing the angle of the throttle blades in the baseplate and the full open position of the airflaps in the airhorn. For really big power levels you'll see some improvement removing the outer booster rings to get the larger CFM units up to 900cfm.

The other MAJOR improvements in all cases are fuel delivery and installing the correct fuel inlet seat/float and getting the fuel pressure up to par. For some reason with these things, and the last time I looked it was 2024, folks are still regurgitating and following old/outdated information on many things. Top of the list is that a Q-jet doesn't like, want, or need high fuel pressure in a performance application. Nothing could be further from the truth, IF you are using a later design made in and after 1969 when they moved the hinge pin location to improve leverage to keep the needle on the seat with much smaller floats.

On my 1977 Pontiac Q-jet I've tried N/S assemblies from .135" to .149" and fuel pressure to and past 10psi and never had a single issue once I moved to a superior fuel delivery system with an electric pump, regulator, return line, and 8AN lines/fittings everywhere. I did see some issues when I tried to get a high pressure/high flow mechanical pump to make the grade there and quickly moved away from it. I suspect, but not sure that the pulsations from the mechanical pump stopping/starting fuel flow with each stroke may "push" the needle off the seat past about 9psi as I had some minor flooding issues during that testing. :Even then I only saw momentary flooding on really hard braking, but no issues on hard runs on the street or at the track aside from the pump not being able to keep in in low gear past about 4500rpm's with good traction.

That deal always puzzled me as well as you'd think a 120gph mechanical pump would easily feed 500hp and a car running into the mid-11's. Even so every single time I've tried that deal I've came up short, and learned that it is just better to "push" most of or all of the fuel with a rear mounted electric pump than to "pull" on it with an engine mounted mechanical pump........FWIW......