Oversize Engine Valves

Cal Grinding, Inc. introduced CalValves in 1987 as an oversize (+ 0.008 in.) solution for a local engine remanufacturer that asked for a less expensive alternative to O.E.M. engine valves. We developed a remanufacturing process that utilized the customer's existing valve core from their disassembled engines. Since that time, our process has evolved and our equipment and manufacturing methods have improved. Today we are not only able to offer our customers oversized engine valves, but valves that are customized to their exact specifications.

The concept behind using oversized valves is simple. It allows the engine remanufacturer to restore the worn valve guides rather than knurling, lining, or replacing them. For heads with integrally cast guides, this is the perfect solution. The worn guides are restored to a slightly larger, better than new condition through reaming. Most new guides have bores with surface finishes between 60 and 80 µin. Ra right from the box, but a guide that is wet reamed with our reamers will typically have a finish of bewteen 10 and 25 µin. Ra. A smoother finish means less friction and less wear.

Our manufacturing process allows us to apply hard chrome to the valve stems at any thickness you desire. We then finish grind the stem to your specified diameter. Since we also offer custom sized reamers, we will work with you to get the stem to guide clearance that you desire. We can provide properly sized reamers that take into account your stem size, your reaming method, and your desired clearance. The end result is hard chrome plated valve stems and smoother valve guides that are installed in a fraction of the time that it would take to replace the guides.

The time and money that you will save is significant and you'll have a better valve train! Of course, if you still prefer to replace the guides, we can provide you with stems returned to the O.E.M. diameters. In that case, you'll appreciate having the hard chromed stems to stand up against the rougher aftermarket guides.

There is much more to CalValves than just oversized stems. CalValves are remanufactured and "adjusted" to meet your needs. Every valve is overhauled from head to toe tip. You not only control the stem diameter, but you control a dozen other features as well. Virtually every machining operation is held to tighter tolerances than other aftermarket valves.