I’ve been building stroked and big-bore V-twins since the mid-1970s. Back then, to get the correct-width manifold for your new creation, you had to just measure the cylinder height (from base gasket surface to head gasket surface) and send that info to S&S. Since the only heads available were reworked H-D ones, S&S would know what the gap between the two intake ports would be and send you the correct
manifold with its carburetor.
Those were simpler times. With the huge selection of billet heads available, there’s no way S&S, or any other manifold supplier, can know what manifold to send you armed with just a cylinder height. Now, the only way to get the correct manifold is to measure the port-center to port-center distance between the two intake ports. Okay, you can also order the entire range of manifold sizes and just keep the one that fits best. But that’s going to be a pain in the butt for the manufacturer or very expensive for the builder, depending on who gets stuck with all the unwanted manifolds.
So S&S, smart dudes that they are, have designed an easy-to-use manifold measuring kit. As you can see in the photo, one method is to bolt two of the kit’s measuring fixtures to the cylinder heads using the manifold mounting boltholes. (The kit also has fixtures for Shovelheads and Ironheads.) These fixtures give you convenient and parallel surfaces to measure between. It also gives S&S a known point of reference, so it can accurately know what manifold width you need.
Also included in the kit are fixtures, so you can measure the length of an existing manifold. Just slip the S&S fixtures over the ends of the intake runners of the manifold and measure the distance between the parallel surfaces of the cone-shaped depressions in the fixtures. AIM
–Chris Maida, as published in American Iron Magazine, the world’s best selling Harley magazine.
S&S Cycle Inc.
235 Causeway Blvd., Dept. AIM
La Crosse, WI 54603