3-3/4 inch tall boring spacer. Included in part # 53-0035 boring fixture kit. Designed for boring stock crankcases of Harley-Davidson Twin Cam 88 engines to accept S&S Super Sidewinder 4 and 4-1/8 inch bore cylinders. This spacer allows the cases to be bored without removing the cylinder studs. S&S Part #: 53-0037