Everyone’s heard the saying that cylinder heads make power. While there is a lot of truth to that universal law of engine building, it’s only half the story. Pair a great set of heads up with a mismatched camshaft, and the resulting power curve will reach mediocre heights at best. Take, for instance, GM’s latest crop of LS small-blocks. Their beastly rectangle-port heads move massive volumes of air, but when matched with rinky-dink OE cam profiles, they leave equally massive piles of horsepower on the table.
Consequently, it’s not surprising that a mild aftermarket hydraulic roller cam will typically add an extra 50-75 hp on one of these motors. Furthermore, in the ranks of ultracompetitive drag racing classes, like NHRA and IHRA Pro Stock, he who turns the most rpm often crosses the finish line first. In this arena—rpm, not cfm—is the limiting factor in power production, and efforts to stabilize the valvetrain are ground right into the cam itself. That’s another way of saying that camshaft technology is extremely important, and with Pro Stockers now turning 11,000-plus rpm, that technology has obviously come a long way.
Leading the charge in valvetrain development is COMP Cams, a company that needs no introduction; they have so many wins and championships in the amateur, sportsman, and professional ranks that everyone stopped keeping count. In recent years, the company has spent an obscene amount of R&D and upgrading to the latest and greatest CNC grinding machinery that the industry has to offer. Additionally, these impressive pieces of hardware have been supplemented with state-of-the-art camshaft gauges that can measure a lobe profile to the tiniest fractions of an inch. Combine all that with world-class training and personnel with a streamlined production process, and the result is a staggering rate of progress in a very short period of time. What this means for street cruisers, weekend warriors, and professional racers alike is a balance of power and reliability that the industry has never before witnessed in the past.
To get a better idea of how it all works and how far the industry has come, we had a long conversation with Billy Godbold of COMP Cams. As someone trained as a nuclear physicist, who spends his days pushing the limits of valvetrain development, Godbold is widely regarded as one of the top camshaft designers in the business, and Chevy High Performance was lucky enough to pick his vast knowledge base for your benefit. Here’s what he had to say.
When I started at COMP Cams over 17 years ago, the aftermarket was using Berco manual cam grinders that were developed in the ’70s. Before the Berco models came about, Norton and Storm-Vulcan both offered manual grinding machines, and some people built homemade grinders. The Berco cam grinders are excellent machines if kept in good repair. The main limitation of these grinders is the quality of the master cam and the care and capability of the craftsman operating the machinery. It was only about 10 years ago when we slowly began making our masters on a Landis 3L machine, but then finish ground camshafts for NASCAR Cup, NHRA Pro Stock, and even CART customers on a manual Berco grinder using the Landis master.
If the limit of a Berco-style manual grinder is the master and machinist, the first limit of a CNC grinder is servo chatter, and the second limit for the aftermarket is cam changeover. The Landis CNC grinders were the first to satisfactorily address chatter back in the ’90s. Their machines are very robust and the servo controls are excellent. We bought two Landis 3L grinders in the late ’90s when an OEM production line closed. These machines were exceptionally good, but our biggest hurdle became changing over from one grind to the next. We also purchased a Toyoda grinder about that same time, but we always had more issues with chatter on the Toyoda grinder; it used very hard CBN grinding wheels compared to the plastic-bonded wheels of our Landis grinders.