The “30-30 Duntov” camshaft is an iconic piece of Chevrolet performance history, particularly revered among enthusiasts of classic Corvettes and Camaros. This mechanical marvel, designed by the legendary Zora Arkus-Duntov, Chevrolet’s first Director of High Performance, was engineered to deliver high-revving power for the small-block Chevy engines of the 1960s. However, deciphering the exact specifications of the 30-30 cam can be confusing, as various sources list slightly different figures. This article delves into the details of the Duntov 30/30 Camshaft Specs, exploring its origins, performance characteristics, and the nuances that contribute to its legendary status.
The 30-30 camshaft was originally developed for the 302 cubic inch small-block V8 engine, most famously used in the Z/28 Camaro. This engine was specifically built to compete in the SCCA Trans-Am racing series, which had a 305 cubic inch displacement limit. The 30-30 cam was a crucial component in achieving the high-RPM horsepower needed for racing success while still being available as a factory option for street cars.
One of the primary points of discussion around the 30-30 cam is its advertised specifications. Historically, and even today across different suppliers, there are variations in listed specs. A commonly cited specification for the original GM 30-30 cam is approximately .452″ intake and .455″ exhaust lift, with a duration of 229 degrees intake and 237 degrees exhaust duration at .050″ tappet lift. Overlap is often cited around 78 degrees. However, some sources, particularly aftermarket suppliers, list duration figures closer to 254 degrees for both intake and exhaust when measured at .050″. This discrepancy often leads to confusion when enthusiasts try to understand the true nature of this camshaft.
Image: Assembling a Chevrolet 302 engine, the original application for the Duntov 30-30 camshaft.
The variance in duration figures can be partly explained by different measurement methods and the influence of valve lash. Valve lash, the small gap between the rocker arm and valve stem when the valve is closed, plays a significant role in camshaft performance. The original 30-30 cam was designed to operate with a valve lash setting. Different valve lash settings can effectively alter the duration and lift seen at the valve itself. It’s been noted that the initial lash specification for the 30-30 cam was .025″/.025″ (intake/exhaust), later revised to .030″/.030″ to improve idle quality, especially in fuel-injected applications. Tighter lash settings generally result in increased duration and lift at the valve, which can enhance top-end power, as experienced by some racers who experimented with very tight lash settings on this cam.
Experiences shared by users highlight the real-world behavior of the 30-30 cam. While it’s known for its aggressive sound and high-RPM potential, some found it less than ideal for low-end torque, particularly in heavier cars or with less favorable gearing. One user mentioned it being a “dog” below 40 MPH in a convertible with 3.07 gears, emphasizing the cam’s nature as a top-end performer, best suited for higher RPM ranges and appropriate drivetrain configurations. However, the aggressive sound alone was enough to deter street races, showcasing its intimidating reputation.
In conclusion, the Duntov 30-30 camshaft is a product of its time, designed for racing homologation and high-revving performance in specific Chevrolet engines. While the precise “30-30 camshaft specs” might be debated due to variations in measurement and lash settings, the core characteristics remain: a high-lift, moderate-to-long duration camshaft optimized for top-end horsepower in small-block Chevy engines. Its legacy continues to resonate with classic car enthusiasts seeking that iconic 1960s performance sound and feel.
