Designed for use with our performance camshafts and are a perfect fit in the stock Ford Focus SPI / CVH engine. These are hydraulic lifters and work well in all situations with flat tappet cams. The proper break-in procedure must be used when installing new lifters on a old or new camshaft. Standard type oil with a higher zinc-phophorus content must be used during the brake-in period along with using a brake-in moly lube on the bottom surfaces and camshaft lobes. These lifters WILL NOT work on a roller cam. New lifters MUST be used on all new cams or  the warranty is void.