Installing a hydraulic roller cam in a traditional small-block Chevy is slightly more complicated than a flat tappet version because the roller requires limiting fore-aft cam movement in the block. Of course, there's no free lunch and a roller cam and lifters are much more expensive than flat-tappet versions. Roller lobes allow much more lift for roughly the same duration. The smarter move is to just upgrade to a hydraulic roller-style cam. A larger lifter (like a Ford 0.875-inch diameter versus 0.842 for Chevrolets) would help, but using Ford lifters would mean subjecting the engine block to expensive block machining. This limitation is set by the diameter of the lifter. This amount of lift is restricted in terms of lift per degree of duration. The compromise with flat-tappet camshafts is that in order to increase lift, there's a limitation on the amount of lift you can create. We could have jacked up the duration with a flat-tappet cam, but that would have made the engine too radical for the street. While this worked, it was obvious that we were going to need more duration to go any further. We tried pushing the lift envelope by adding 1.6:1 rocker arms to bump the lift. The RPM heads had the potential to flow more air if we could just add more lift.
