Plastic tubes get it done for grass-roots racing

Automotive Design & Production, May, 2004

Willy's Carburetor and Dyno Shop in Mt. Carmel, Illinois, is one of the handful of places (in the north, there are buckets-full in the south) that is a tuner source for the teams in NASCAR Nextel Cup and Busch Series. It goes without saying what Willy Krup and his people specialize in. Although the teams at that level can afford machined aluminum components, Krup, when looking into doing some work for the grass-roots Dirt Late Model and UMP Modified oval track classes, determined that there was a definite problem--the fact that when you're turning left at speed for practically a whole race, the fuel is pushed to the right side of the carburetor's float bowl, thereby almost starving the jets for the left side of the engine. He came up with one solution, but knew that it was a bit on the costly side: aluminum fuel pickup tubes that return the fuel to the fuel-metering block.

So Krup decided to go plastic. He worked with Holzmeyer Die and Mold (Princeton, IN), which initially produced a nylon tube. Which proved to be insufficient to the rigors of the sport, such as the alcohol fuel (which softened the tubes, and compromised the threaded retention bolt) or the heat-and-cool cycles typical of the race (with the high temps causing the nylon pickups to shrink as much as 0.003 in.).

The alternative that worked was a heat-stabilized, glass-reinforced polyphthalamide, AMODEL AS-1133 HS from Solvay Advanced Polymers (Alpharetta, GA). Not only does it meet the physical requirements of the racing, but according to Carolyn Catt, material manager at Holzmeyer, it "is easier to mold than the reinforced nylon." And it's affordable.

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