Triumph 500 650 Pre-Unit and Unit Tappet Guide Block Inlet/Exhaust (1) 1946-65 Kibblewhite PN# 70-1477K-2nd

*This is a clearance item and the internal bore has machining defects as shown in the photos! Sale on this item is final. WE’VE DONE OUR BEST TO DESCRIBE AND ILLUSTRATE ANY KNOWN DETAILS OF THIS ITEM. PLEASE REFER TO PHOTOS AND DESCRIPTION AS ALL SALES ARE FINAL ON THIS CLEARANCE ITEM! Kibblewhite tappet guide blocks are manufactured in the US using a proprietary cast iron material. The O.D. measures .920″ where the pushrod tube fits over the top of the block. Shoulder thickness is .125″, and the O.D. of the bottom of the guide block is 1.0005″. There is a groove for an o-ring under the shoulder for oil sealing against the cylinder barrel flange, a significant upgrade from the factory original 70-1477 guide block. Lubrication to the tappet stems is provided by drillings that pass through the block longitudinally, allowing oil to drain down the pushrod tube from the rocker box. The tappets are a sliding fit in the guide block bores and if the tappet stems or bores in the guide block become worn excessively, mechanical clatter may result. Kibblewhite guide blocks are machined to a “maximum metal” condition and require the bores to be sized with a piloted reamer and finished with a ball hone to achieve proper running clearance and surface finish after the block is installed. The guide block is an interference fit into the bore of the cylinder barrel. A special drift is used to set the block into its bore. It is advisable to freeze the guide block for several hours and to heat the bore surround under the cylinder barrel flange prior to fitting the block. It’s critical that the locking bolt hole in the guide block is in perfect alignment with the threaded hole in the cylinder flange. Installation of the guide block requires precision and skill and may be best left to a professional mechanic or machinist.   The product images shown are for illustrative purposes only and may not be an exact representation of the product received. Manufacturers occasionally make minor cosmetic changes to items, such as color, finish, label, or design. These changes do not impact the item’s function or compatibility. Please contact us if you have specific concerns regarding appearance.