Tap and die sets include a gauge that calculates threads per inch. Select the corresponding die that matches with the reading on the thread per inch gauge, and set the die in the handle that comes with the set.
The IROC-Z model of the Chevrolet Camaro first made its public appearance in 1985 as an add on option to the 1985 Camaro Z28 model. But its origin began long before that. IROC stands for International Race of Champions which is an automobile racing series similar to what NASCAR is.
In 1987, the Z28 convertible was introduced. An outside firm, ASC (Automotive Specialty Company), did the conversions. Only 744 Z28 convertibles were sold in 1987. The big performance news was the return of the 350 V-8 in the form of an optional IROC engine. The 350 was rated at 220 horses, and was only available in IROC-Z coupes.