Carburetor Jet - Carburetor Jet - Standard Main Jet - 1/4-32 UNF Thread - Hole Size 0.0755 in. - Pair. Features: Carburetor Jet. Holley products have been the undisputed leader in fuel systems for over 100 years. Holley carburetors power every NASCAR Sprint Cup team and every NHRA Pro-Stock champion. Holley's products include performance fuel pumps, fuel injection, intake manifolds, cylinder heads & engine dress-up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies, Hooker Headers, Flowtech Headers, NOS, Weiand, or Earl's, Holley products can give you the edge you need over the competition.