A correctable weakness in the XK Jaguar cylinder head is tappet guide movement. Even in casually driven street cars, the guides can work loose and cause untold damage. Our hold-down kit is the ounce of prevention needed to hold the guides in place. The head must be drilled and tapped to accept the mounting screws, which can be done with the engine in the car. Complete set as shown, top. The inset photo above illustrates the placement of the hold-down. Manufactured in the USA by XKs Unlimited.