Kibblewhite Precision Machining products are the choice for demanding engine builders and represent the finest quality parts and tools available. This is the exhaust guide block with a machined groove to accept an o-ring, and an oilway for the tappets, as fitted to Triumph B range 650 and 750 twins from 1969-1979. Can also be used in the inlet guide block position where there is no pressurized oil feed present. Check your parts book for compatibility.
Kibblewhite tappet guide blocks are manufactured in the US using a proprietary cast iron material. The O.D. measures .984″ where the pushrod tube fits over the top of the block. Shoulder thickness is .182″, 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. An oilway is machined into the lower half of the block to pressure feed the tappets.
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.
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