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By Mike Bumbeck

In any form of heads-up “index” competition, the theory is the same:  If you could cut a spot-on “four-oh” light, and everything on the car was working perfectly on the dial, you would win every time!  Out on the track, of course, events usually play out a little differently then while driving the barstool or the Lazy Boy.

Variables, especially those of the fuel-curve variety, are the archenemy of ET consistency. With engine displacement in the super categories getting into the supersize ranges, ever-increasing demands are placed on fuel delivery of the traditional, single-carburetor setup. Getting the carburetor to deliver the correct amount of fuel and air throughout the entire range of engine RPM based on engine demand is the key to winning; it can mean the difference between going rounds or pushing back onto the trailer and going home early.

WOT Did You Say?

Determining what the carburetor is supposed to do at wide-open throttle (WOT) when the engine is at full boogie is one thing, but getting fuel delivery to behave on the way to WOT is another. A carburetor that bogs out or stumbles on its way to the top is never going to get there quickly and consistently enough to light up the win light. The real trick is delivering the right amount of fuel at precisely the right time to get the engine going as quickly and consistently as possible.

At WOT, things add up to a fairly predictable equation. However, as converter stall, torque loads, throttle stops, pneumatic shifters, and track and air conditions get factored into that same equation at intermediate fuel delivery, it becomes much more complex. In the case of a throttle-stop racecar, nothing about the setup as a whole is designed to be run at the unnatural, low- rpm condition that the throttle stop creates after the initial hit. Unless the carburetor is specially prepared for this unnatural spot on the curve, a lean or rich condition can occur, and the engine will stumble. Worse, if the shift timers are kicking in at the same time the engine is stumbling, the dialed elapsed time will almost certainly go astray. Thus did E-Carb Competition Carburetion (Everett, Wash.) create its T/S-1050 calibrations specifically for throttle-stop applications.

E-Carb’s T/S-1050 (“Throttle-Stop Dominator”) comes with everything shown here, and more. E-Carb starts with bare 1050 Dominator castings from Holley and steps them up to the next level.
Since a carburetor begins its life at idle, great attention is paid to the transition slot in the throttle body, and the entire low-speed circuit. Poor fuel atomization will occur in the absence of a smooth transition between idle, intermediate, and main fuel circuits.
Stock-vs.-E-Carb booster designs: An annular-discharge booster features holes around the entire circumference of the booster for improved fuel atomization. Different boosters are fitted according to signal amplification demand at hand, or at foot – as it were.


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