Cam Face Crown & Finishes:
Hy-Lift Johnson Inc. has worked with all of the major OEM Camshaft manufactures and most of the performance Camshaft pioneers over the last 70 years on the proper Cam Face Crown and Finish. The Cam Face is not flat but actually has a spherical crown ground on it. This crown height varies from engine manufacture to engine manufacture but most are between 0.0015” to 0.0025” high. Some very high performance customers require a lower crown (0.0007” to 0.0012”) to handle extreme loads but there is always some amount of crown. Our Testing and development on the Crown height and finish is extensive. We have the capability to offer any crown height as well as finish. Our grinding pattern has been developed after years of testing and it promotes the best oil propagation across the Cam Face needed for the best initial Camshaft Lobe to Lifter break-in possible. All of our Cam Face Profiles are ground and NOT polished. Some suppliers are taking inferior Cam Face surface finish and “hand polishing” them to a “mirror” surface to make them look good. The problem with hand polishing is that the polishing process removes more material from the edge of the Cam Face than it does from the center which alters the critical Crown profile and height. We hold our Cam Face Crown geometry to a maximum of 0.00040” and there is no way that kind of tolerance can be achieved by “hand polishing”. Also the grinding pattern on the Cam Face is necessary to promote oil propagation to cool as well as lubricate the mating surfaces during the crucial initial break-in procedure. We can offer ground surface finishes to very close to a mirror without altering the Cam Face Crown and still retain some slight pattern to promote that needed oil propagation. So if you need to see yourself use the mirror in the bathroom and leave the Cam Face surface finish to the people who have been leading that field for 70+ years!
These two lifters were “hand polished” and sent to us to measure the Crown. Both failed our quality miserably for Crown Height (both were off our gage at over 0.0035”) and squareness. You can even see how they removed extra material in the corner because the polishing removed more at the edge.