If one thing truly leads to another, you can say a leaky oil pan in our '72 Nova SS led us to this cam swap. We had to pull the Dart 509 out of our car to swap in a new Moroso oil pan, and we felt we were leaving a bunch of power on the table with the hydraulic roller cam profile that was in our Rat, ergo, we put in a call to Comp Cams for one of its ultra-modern solid street roller designs.
We've learned from years of previous cam swap testing that a cam with the same duration with roughly 0.100-inch more valve lift has always meant a stronger running engine with a smoother idle, more low-end, mid-range and top end power. That's what we went for here. More peak torque at a lower rpm for better bottom-end grunt, and gains in peak horsepower at a higher rpm for a broader powerband and top-end charge make this type of cam swap a win-win.
Another benefit is additional vacuum for a better signal to the carburetor, which translates to better throttle response and fuel efficiency. For our SS509 Nova project, the added vacuum to the power brake booster for our four-wheel discs means less pedal effort and improved feel, without having to resort to a vacuum can or pump.
When choosing a cam, it's better to make a conservative choice for your combination's intended purpose. Just remember: the stick with the most lift for the same duration will make for a more responsive engine. Choose one from the catalog that is recommended to match your combination (engine size, compression ratio, heads, induction, exhaust, gear ratio, converter stall, vehicle weight, rpm range, etc.), or call one of the cam companies—they have experts on their help lines. If you look up the cams involved in this swap, you'll notice they are only a middle choice of the street roller-type, yet they make lots of power. Never choose a race-type cam for your street driver, or you'll have a ride with terrible drivability and efficiency.
Technology advancements in camshaft/valvetrain design and durability have come a long way in recent years. We took advantage of this and put it to use on our Nova to have even better drivability and efficiency. One thing we must mention is besides gains in drivability and power, the side benefit is improved fuel mileage. We didn't measure it, but we used much less fuel driving to the dyno and the strip—and now the exhaust turndowns are a light grey color instead of medium brown. It's quite possible that mileage improved by two to three mpg—maybe we stumbled on the ideal cam for our combination. Read along and see the cam installation and how we made out dyno and strip testing bumpsticks.