This sounds ridiculously basic, but over the years we’ve seen many examples where the car owner/tuner has made changes to the engine and neglected to re-check the maximum throttle opening — better known as wide-open throttle (WOT). We recently visited our friends at Westech in California where Steve Brule was testing a 512ci Mopar Wedge street engine.
The first pull for power on this engine revealed well over 640 lb-ft of torque and over 620 horsepower. On the second pull, the power dropped slightly with an even further loss of power on the third attempt. After checking the obvious things like a spark plug wire off, a dead cylinder, or a rocker out of adjustment and with no metal in the oil, Steve was pondering his next move when he discovered the carburetor mounting studs were loose.
With the carb not tight, this allowed it to move laterally because the carburetor used one of those universal throttle plates drilled for both the standard Holley 4150 and Dominator 4500 bolt patterns. When the carburetor moved, it also moved the throttle linkage which prevented WOT. Steve readjusted WOT and on the next pull the power picked up over 30 lb-ft of torque and a similar horsepower increase. The adjustment was quick and easy and the resulting power increase was impressive despite the minor difference in throttle opening.
To reinforce this approach, the guys who run the chassis dyno at Westech Eric Rhee and Ishmael Candia tell me that anytime they pull a car onto the electric rollers, the first thing they always check is WOT, especially with street-driven cars. They often discover the throttle linkage needs major adjustment. With engines, as with life in general, it’s the little things that can make a big difference. Especially when it really is free horsepower.