[Cliff R]

The article in question here suggests 4-6psi but doesn't mention what carb is being used or the size of the fuel inlet seat. I suspect that the author was either using a 1968 or older carb for the testing, didn't test at all, or regurgitating old/outdated information on the ability of a Qjet to work well with higher fuel pressure.

There are pics of later Q-jets in the article however. The later Q-jets have a revised hinge pin location and much smaller float. If you were using a later carb you could have easily used a .145 or even a .149" N/S assembly and 7-8psi fuel pressure and been fine at your power level.

I did some testing at the track with my 1977 Pontiac Q-jet and both fuel pressure and larger fuel inlet seats. WIth the standard .135" seat I didn't have any issues until I dropped the pressure to 6psi. I could feel the car start to surge slightly mid-track and if I went 5psi or lower it would suck the bowl completely empty and the car would nose over, then recover. If I turned the pressure up to 7 psi or higher no issues.

I went on to test .140, .145 and the .149" seat and no issues anyplace until I turned the pressure down below 5psi. I settled on using a .145" seat and 7.5psi fuel pressure and never had a single issue anyplace even when I made upgrades to make the car faster at the track or went to more powerful engines. So fuel pressure is your friend with these things. I need to mention here that NONE of the things mentioned above worked at all until I upgraded the fuel system for the power of the engine and performance capability of the vehicle.

I also tried to find the limits with fuel pressure and turned the regulator up to 10 and then on to 12psi and no issues anyplace. Since I was able to keep the carb completely full on a hard run with much less pressure I settled in on 7.5 psi and called it good.

As far as hacking up your carburetor or going nuts with a grinder and sanding roll I don't really see any problem with all that. To date I've never seen a rule book when it comes to modifying anything associated with your engine to help it out some. In the real World of high performance and making power however, very little of what I see done actually helps with these sort of things.

For example I've seen folk grind and polish the runners in factory iron heads to the brink of extinction and not do any work in the bowls and short turns or even worse screw that part of it all up. Then they call them "ported and polished" but never did a single air flow test to see if any of it actually helped anyplace and for sure no "back to back" dyno or drag strip testing of any sort. To this day I cringe when I hear the words "ported and polished" when it comes to cylinder heads. I truly believe that most of them were better before they touched them....FWIW.

Same with carburetor modifications. I've had carbs come in here with the entire choke areas machine clear off and venturi areas ground clear out of them leaving pretty much a straight shot past the boosters to the throttle body. Did any of it help? Who knows but for sure without a choke a cold start isn't going to be nearly as easy when you need to move the car out of the garage when it's 30 degrees outside.