This creates what engineers call high-unit loading pressure. A roller follower, depending upon the diameter of the wheel, places a much smaller portion of the wheel against the lobe. A mild flat tappet cam design allows a relatively large portion of the lifter to contact the lobe. The main reason for this has to do with contact area. Both the camshaft and the roller itself must be very hard to be durable. This obviously reduces the friction of the two surfaces, but also requires a much harder and more durable camshaft and roller follower material. The roller follower employs a wheel that, as you can imagine, simply rolls over the surface of the lobe instead of sliding.
Mild cam 350 small block Patch#
Because of the smaller contact patch the roller presents to the cam, most roller cams are steel- much stronger alloy pieces than their cast-iron flat tappet cousins. The hydraulic roller tappet also has similar functions to flat tappet hydraulic tappets in that the small internal piston creates a cushion of oil that automatically compensates for growth as engine temperature expands the block and heads.Ī roller cam is differentiated from a flat tappet camshaft both in strength and by the type of lifter used. A mechanical roller tappet functions much like its mechanical flat tappet cousin and requires a lash, or clearance, in order to operate properly. Just like flat tappet cams, the two types of roller cams are mechanical and hydraulic.
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Mild cam 350 small block full#
This Tech Tip is From the Full Book, HIGH PERFORMANCE CHEVY SMALL BLOCK CAMS & VALVETRAINS. But roller cams and roller followers soon became very popular with race-engine builders, and have been with us ever since. Once metallurgy improved, flat tappet cams were preferable because they were cheaper to manufacture. In fact, roller cams are about as old as the internal combustion engine itself, which was first created over 100 years ago for diesel engines! In those early days, roller cams were created because flat tappet cams experienced excessive wear.
If a chic term exists in the performance aftermarket, it is probably “roller cams.” Hot rodders tend to follow the lead of the OEMs, and when GM began building hydraulic roller cam engines for the TPI Corvette and the Camaro in the late 1980s, it started a whole new trend in street hydraulic roller camshafts.