Technology has had a positive effect on traditional Pontiac performance. Today’s monster mills perform considerably better on the dragstrip than yesterday’s race engines, but are often so reliable and docile that they can be driven on the street regularly. While much of that can be attributed to cylinder-head and intake-manifold design, as well as fuel and ignition-system advancements, modern valvetrain components are equally as responsible.
A roller camshaft is among the most popular modifications that can improve both performance and driveability. Modern hydraulic rollers are much more reliable than ever before, and because they’re not susceptible to lobe and/or lifter failure related to modern-spec oil, they are growing increasingly popular. Many shy away, however, when they learn of the relatively high cost when compared to a $200 flat-tappet camshaft kit.
While many hobbyists understand the benefits that hydraulic-roller camshafts can offer, rarely has it ever been quantified in a back-to-back testing scenario, so that’s what we did. We ordered a custom-spec hydraulic roller from Comp Cams and compared its performance to two high-performance flat-tappets that we tested previously. Follow along as we share the results!
Our ’76 Trans Am is a dedicated street car that’s often driven in stop-and-go traffic and for relatively long distances. If you’ve read “Affordable Attitude Adjustment” (HPP, June ’11), you know our quest was to achieve maximum performance while maintaining maximum driveability from our relatively mild combination, which is assembled mostly of original Pontiac components. In that article, we went to C&S Dyno Shop in Omaha, Nebraska, to compare two high-performance hydraulic flat-tappet cams from Nunzi’s Automotive.
On the Mustang-brand chassis dyno, our moderately-built 467ci generated 355 hp and 402 lb-ft of torque at the rear tires with the 2043NHL cam (244/252 degrees at 0.050-inch). We then installed the slightly smaller 2042NHL (232/243 degrees at 0.050-inch) and as expected, its wider lobe-separation angle and lesser duration significantly improved driveability, while maintaining an equal amount of rear wheel torque (403 lb-ft) but reducing peak horsepower to 346 at the tires.
Though the driveability improvement was the exact result we sought, it didn’t take us long to begin exploring ways to restore the peak horsepower we lost, but we weren’t willing to compromise the newfound street manners. A number of professional Pontiac builders recommended a hydraulic roller.
A roller camshaft has a distinct advantage over a flat-tappet. The lifter body is fitted with a roller wheel that reduces friction, which not only improves efficiency and can provide a slight fuel economy increase, but it also allows for a lobe design that opens and closes the valves at a quicker rate. That keeps the valves open longer at mid-to-high lift, improving cylinder fill and performance. The quicker lift rate also allows the roller wheel to stay on base-lobe longer, improving efficiency and reducing emissions.
To explain how this occurs, consider two similar camshafts. One is a hydraulic flat-tappet and the other a hydraulic roller, and both share identical 0.050-inch duration specifications. A hydraulic roller will contain less seat-to-seat (or advertised) duration, and that reduces valve overlap, improving idle quality and increasing vacuum. A hydraulic roller will also contain more duration at 0.200-inch on up, and that can extend and improve high-rpm performance.
Adding hydraulic action to a roller cam provides consistent performance and quiet operation. These positive attributes are what make roller cams ideal for modern auto manufacturers. When hydraulic rollers were first developed years ago, reliability was inconsistent, but modern production techniques have made them extremely durable, offering thousands of miles of issue-free performance.
Hydraulic Rollers for Pontiacs
Many companies, such as Comp Cams, Crane Cams, and Crower Cams, offer a wide array of Pontiac roller camshafts, hydraulic roller lifters, and all other components required to operate reliably to at least 6,000 rpm, and possibly more.
We wanted to maintain low-speed street manners that were as good as part number 2042NHL, and hopefully as much top-end performance as with the larger 2043NHL. Since we’d already measured the performance of both flat-tappet cams and no other parts would be changed, a follow-up chassis-dyno session would give us the chance to accurately determine how much can be gained from a hydraulic roller.
[1] A hydraulic-roller camshaft...
[1] A hydraulic-roller camshaft is a very popular modern upgrade. We sourced a custom unit from Comp Cams for our 467-inch Pontiac V-8 and compared its performance to similar-spec hydraulic-flat-tappet grinds.
[2] It’s easy to understand...
[2] It’s easy to understand the advantages that roller cams possess when placed next to a flat-tappet. These two have similar 0.050-inch duration specs, but the roller-cam lobe profile (right) is much more aggressive.
[3] Comp Cams produces a wide...
[3] Comp Cams produces a wide array of top-quality valvetrain components to accommodate installing a hydraulic-roller camshaft into a Pontiac V-8.
[4] We opted for Comp’s high-quality...
[4] We opted for Comp’s high-quality Ultra Gold roller rocker arms during our swap. Our existing rocker arms were 1.6:1 ratio; we planned for 1.5:1 units with the new cam.
[5] Out with the old…
[6] …and in with the new....
[6] …and in with the new.