Under The Curve

A new lifter has a crown on the bottom edge, and a new camshaft has a tapered lobe face that allows the lifter to rotate on a wide contact area. Because of this unique wear pattern, only new lifters should be installed and broken-in with a new camshaft.

The first step to properly breaking in a new camshaft is to read the manufacturer's instructions. The second is to apply the cam manufacturer's special lubricant to a clean camshaft and then install the cam into the engine. It's best to use some sort of a cam handle so that you don't have to handle the lobes.

With the cam installed, drop each clean and properly lubed lifter into its bore. Remember that after initial startup, break the cam in per the manufacturer's instruction.

Roller cams use a small, hardened wheel on the bottom of the lifter to follow the cam lobe. Roller lifters help to reduce friction and/or to allow a cam design with a more aggressive profile (more duration for the same amount of lift).

To accurately determine the location of the cam in the engine, a degree wheel is installed on to the crankshaft snout and measures the relationship between the camshaft and the TDC of the number-one piston.

To install roller lifters in an engine designed for flat-tappet cams, special roller lifters that feature a special tie-bar to keep the lifter from rotating in a circle on the lobe, like these, are used. Unlike flat-tappet lifters that form a wear pattern to the originally installed lobe, roller lifters may often be reused on different roller cams.

Factory-equipped roller lifter Chevy V-8s use these stamped metal pans to hold the stock roller lifters in place. Beginning in 1987, factory fuel-injected small-blocks began to use roller lifters.

Cam cards hold a wealth of information. This card is for a Crane hydraulic dual-pattern camshaft with 222/234 degrees of duration measured at 0.050-inch lift and 0.467/0.494 valve lift. Guard the cam card with your life.

This graph illustrates lobe lift in inches on the vertical axis (y axis) and degrees of duration across the horizontal axis (x axis). This particular camshaft has 0.470-inch lift and 224 degrees of duration measured at 0.050 lobe lift. The blue triangular area is the overlap area, which is where the exhaust valve is just starting to close and the intake is just beginning to open. To determine the lobe separation angle, add the exhaust lobe centerline (BTDC) to the intake centerline (ATDC) and divide by 2. As an example, if the exhaust lobe centerlines is 116 degrees BTDC and the intake centerline is 106 degrees ATDC we simply calculate 116 + 106 = 222/2 to get 111 degrees. Remember, the lobe separation angle is stated in camshaft degrees and the intake centerline is always expressed in crankshaft degrees.