The Flex-Hone® for Small Block Ford Engines

Small Block Ford Engines are V8 power-plants sold by aftermarket auto parts suppliers and by Ford Motor Company itself. Originally built at the Blue Oval’s engine plant in Windsor, Ontario, Canada, the Ford small block is also known as the Windsor engine. The 351 Windsor block, as its name suggests, is a 351 cubic-inch workhorse that’s significantly larger than the first Windsor engine, the 221 for the Ford Fairlane and Mercury Meteor. Not to be confused with the 351 Cleveland, today’s 351W is marketed as the Racing Boss 351, a crate engine from Ford Racing Performance Parts.

Engine Building and Plateau Finishing
For engine builders like Rog, an automotive do-it-yourselfer who creates his own YouTube videos, restoring a 351 Windsor block the right way means plateau finishing for proper piston ring seating. As Rog explains, the Flex-Hone® tool from Brush Research Manufacturing (BRM) is designed for plateau honing, which “take the peaks off the metal” walls of honed engine cylinders. Typically, when engine mechanics refer to a “honed surface”, they’ve used a rigid hone to affect bore diameter and cylinder geometry. Honing stones are designed for material removal, of course, and these rigid hones leave an intermediate finish.

Plateau Honing for Engine Performance
That’s where flexible honing comes in. By using BRM’s Flex-Hone® tool to remove only the peaks and rough, torn, and folded metal, engine rebuilders like Rog can produce a plateau finish that provides an optimal surface for a new set of piston rings. As Engine Builder Magazine explains, “getting the rings to seat and seal properly requires a ring-friendly finish on the cylinder bores. The cross-hatch pattern that the Flex-Hone® produces supports optimum lubrication, too. By removing surface irregularities, BRM’s plateau hone also helps to prevent metal shavings from winding up in your engine oil.

Flexible Honing – Preparation, Performance, and Cleanup
In Engine Building with Rog, the YouTube mechanic demonstrates how he used the Flex-Hone® tool to refinish the first of eight cylinders in a used 351 Windsor block. First, however, he lubricated the walls of each cylinder – though not with the Flex-Hone® oil that we recommend, and perhaps without as much honing oil as is best. Next, Rog chucked BRM’s cylinder honing tool in a handheld power drill and ran it at between 500 and 800 RPM for 30 to 45 seconds. Although Brush Research recommends warm or hot soapy water for cleanup, Rog simply used a rag and some spray cleaner.

A colorful character, Rog concludes that “the engine is a pump – the better it pumps, the better you feel it in your pants”. Just as proper piston ring seating and sealing are essential for engine power, the Flex-Hone® is necessary for plateau finishing.