Special section--camshafts and valvetrains: Camshaft selection

National Dragster, Mar 7, 2003 by Veney, Todd

Racers who do their homework before selecting a camshaft will be rewarded with A+ performances

Solid lifter, hydraulic, or mechanical roller: Which kind of cam should you buy? That, like everything else when it comes to building engines, depends.

You don't have to be Garley Daniels or Gene Dunlap to choose a cam and degree it in or to adjust valves. And you don't have to race in Pro Stock or B/Altered or any other Comp or performance-oriented category to use a roller cam; the majority of Super Comp, Super Gas, and even bracket racers already do.

Balance your needs and your budget against the cost of upgrading from the hydraulic cam you might be running now to a roller. You know that if you dig into your wallet for the roller, you'll have added lift and duration and an associated increase in cylinder pressure. But your existing cam already is opening and closing the intake and exhaust valves at the right time, synchronizing that with the rotation of the crank, and, most important, not costing you any money. Is a roller cam really necessary? Can you afford it? And do you have the time and the money for the increased maintenance?

A mechanical roller camshaft's higher lift and greater duration make it the only cam for most high-performance applications. Hydraulic flat tappets can be a nice balance between performance and cost, and hydraulic rollers are ideal for street/strip applications, offering many of the benefits of hydraulic flat tappets but with more torque in the same range. Finally, a flat tappet, usually designed for daily-- driver use, can still provide plenty of torque at low rpm.

"Me kind of cam you want depends on what your engine is doing rpm-wise," said Brian Crower of Crower Cams & Equipment "If you only want to rev it to 6,000 or 6,500 rpm, you can get away with a hydraulic cam. Anything over that and you're just bottoming out the guts of the lifter. Budget and rpm are always going to be your determining factors."

Also at issue is the additional (though manageable) maintenance that goes with a roller cam. "If you're a Sportsman-type guy who's not looking for that last tenth of a second in el, you can just get a solid-lifter, flat-tappet cam," said Erson's Tom McGibbon. "But if you decide you want a roller, the maintenance really isn't that bad. Basically, all you're talking about is valve adjustment, and running the valves isn't a big thing for the typical bracket racer."

Still, roller cams aren't for everybody. Some bracket racers do perfectly well with flat-tappet-mechanical or hydraulic-lifter cams. "For a general beginner, a solid mechanical cam is fine," said Howards Cams' Dewey Lehmann. "We give enough instruction in the catalog for the average guy to install it himself. Just ask yourself if you have enough experience to maintain it."

Said McGibbon, "With a good small-block, even in a heavy, dual-purpose [street-and-strip] car, there's no reason you couldn't run in the Ills or 12s with good reliability and good power with a flat tappet. I've seen high lOs out of cars with solid-lifter flat tappets. And for hydraulic cams, high Ils, low 12s shouldn't be a problem. We're seeing a lot more interest there from street-and-strip people."

Crane Cams' Jim Hill said, "The first thing to consider is where to get the greatest reduction in elapsed time. Frequently, more elapsed time per dollar is available by maximizing torque off the starting line than worrying about maximizing power at the top end. Keep in mind that e.t is generally a result of torque and speed is a result of horsepower."

But if ultimate power is the only concern, there's only one way to go. With the roller cam's added maintenance and expense comes an accompanying increase in power. Crower said, "If you're going to turn a lot of rpm and have the budget and can handle the maintenance, you can't beat a mechanical roller for performance."

There are additional maintenance costs as well. As with any flat-tappet cam replacement, you'll need new lifters. They're a must, like changing your filter when you change your oil. The point where the lifter rides on the lobe is under extreme pressure, so the cam and lifters wear in together; skimping there inevitably leads to greater expense down the road. And it's not just lifters; depending on the grind, you'll probably need a complete set of valve springs and retainers, too. And let's just say that replacing lifters and checking valve springs will become a bigger part of your life.

"To get set up with a roller, you have to change so many other things," Lehmann said. "For a bracket-type situation -- one where the engine isn't going to see anything over 6,500 rpm - you can buy a new cam and hydraulic lifters for $175 or so. When you go to a mechanical camshaft, that's going to be another $25, not including springs. And when you get into a roller cam, it really gets expensive: a minimum of $450 for just the cam and lifters."

Despite that, a roller is the cam of choice for a majority of drag racers and is the only high-end option. "Only about 30 or 40 percent of bracket racers use a hydraulic or solid flat-- tappet cam anymore," Lehmann said. "Rollers are a common thing because they're pretty cost-effective for the performance."