Typically, carburettor jets are installed with flat blade screwdrivers, and the slots are damaged to some degree during installation, altering fuel delivery by up to 50 percent. This problem can be solved with COMP Cams MaxJet carburettor jets. These jets are available from 0.100 in. to 0.135 in. increments and are compatible with all known racing fuels. They are easily crossed over from Holley jets, are produced with a 5/16" hex-stock brass, and are installed using a 5/16" nut driver, eliminating the fuel delivery damage caused by slot-type jets. 1/4-32 Thread Size. They are virtually indestructible and provide smooth and precise fuel delivery.