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The carburetor: Quick Fuel Technology Model FX4712

We had a tough time deciding on a carburetor. We talked to a lot of people and that was even more confusing. I finally did what I should have done right away: Call the carburetor manufacturers and ask some questions. That is what I did and Quick Fuel’s tech guys sounded not only interested but very knowledgeable when I started asking about how their carburetor would work in throttle-stop racing as well as Top Dragster racing. They assured me their new 1250 cfm FX4712 (gas model) would be exactly what this engine would be happy with.

They have engineered a raised area just above the venturies of the carburetor to help straighten the air flow, and all the air bleeds are adjustable. They sent the FX4712 jetted with #96 at each corner, .042 squirters and a build sheet that detailed every possible opening and restriction in the carburetor. It was very thorough and it will be easy to call them with real numbers if we want to try something different.

We ordered FX4712 and when I took it to AEM so they could get on the Project 4-Link engine for the dyno session, it did not disappoint. The brake-specific data from the dyno showed excellent fuel curve results. The BSFC on the dyno ran from .39 at 5000 RPM to .42 at 7000 RPM. The mixture stayed rock steady and results were excellent. No jet change needed, floats were right on. It was a bolt-on piece of equipment that impressed the guys at AEM as well.

We have had the Project 4-Link out twice with this carburetor and the idle is very crisp, off idle to the rev limiter is almost instantaneous, and we are very satisfied. Not to mention it made 966 H.P. in 3,000-foot air with spacers that were too small for the throttle bores.

Fuel System: Aeromotive will provide the fuel volume and pressure we need

This is the belt-drive pump (#11105) with the lower-left BBC bracket attached to it. You get the pump, spindle, pulleys and belt with the pump. A couple AN O-ring -12 and -10 fittings and it is ready to go to work.

We had always used a belt-drive pump on Project 4-Link. Personally, I think they are inherently safer because if you hurt an engine or have an accident, as soon as the engine stops the fuel pump stops. Besides the safety angle, I like the lower fuel pressure at idle with a belt drive. This means less pressure on the needle seats while driving the car in the pits or warming it up.