This article is aimed at anyone who's ever sat in the most important room in the house thumbing through a catalog and blankly wondering which cam to pick for a mild-performance small-block Chevy. We know the drill because we've done it: You skip the tiny grinds and figure one of the middle-of-the-pack cams should do the trick. The problem is which one, when there are several bunched together that all sound good?
To illustrate the dilemma, we flipped through our latest Summit Racing catalog and checked out the company’s line of in-house grinds. Skipping the first three weak-suck profiles, we found SUM-K1103, a cam with 214/224 degrees of duration at 0.050-inch lift, intake/exhaust lifts of 0.442/0.465 inch, and a lobe separation angle of 112 degrees. Sounds good. But what about SUM-K1104? That’s got 10 degrees more intake duration and a 0.465-inch intake lift; the exhaust profile is the same, so it’s a single-pattern cam. Sounds better, but wait! There’s also SUM-K1105, a bigger split-pattern ’stick with a hearty 224/234 degrees of duration at 0.050 and 0.465/0.488 lift. That sounds aggressive without being too radical. Since they all cost the same $79.95, why not get a little more bang for the buck? You can see the quagmire we’re quickly spiraling into: Some is good but more is better, and before too long, we’ll be pulling 9 inches of vacuum and sounding like we’re running in Pro Stock Eliminator.
When it comes to cam selection, you can theorize all day long about gear ratios, converters, compression ratios, etc., or you can do what we did: Build an average, mild-performance 350, stab all three cams into it in succession, and run it on a dyno. Since you probably don't have the time or money to do that, we did it for you. And the best part is, you don't even have to get off the throne!
Conclusions
We ran all three cams on Westech Performance Groups SuperFlow dyno with a Holley 650 carb, a Holley Street Dominator dual-plane manifold, a stock HEI ignition, and a set of Hooker 1¾-inch primary headers (see dyno chart, top right). The headers are larger than we would probably use for this engine on the street and likely gained us some top-end power at the expense of torque (we bought a set of 15/8-inch full-length headers from Summit (PNG9001) to use later). All three cams produced peak power with 12 degrees of initial timing (38 degrees total), and, interestingly, all three produced peak horsepower and torque at basically the same rpm points. As you might expect, the smallest cam produced good peak torque, the flattest torque curve, and the best idle vacuum. The middle cam produced 5 more horsepower at the peak with about the same torque curve and a little less vacuumeven so, wed choose the smaller 214/224 cam over the 224/224 unit.
Although it generated the least idle vacuum, the biggest cam produced the best peak torque and horsepower of all three cams tested: 343.6 lb-ft of torque at 3,900 rpm and 304.3 hp at 5,100 rpm. That’s a 15hp gain over the smallest cam with only a small low-rpm torque loss, primarily under 3,500 rpm. As far as we’re concerned, the small loss in area under the torque curve would have a marginal effect on driveability and is more than offset by the hefty increase in power at the top end, especially since it produces peak power and torque in the exact same rpm range as the smaller cam. Also note that the 224/234 cam is identical to that used in our El Cheapo car, and we think it runs plenty good enough for daily driving. In this case, we’re not afraid to say that bigger really is better.
