* Year and specific engine: Small-block Chevys span many years and variations (e.g., 265, 283, 307, 327, 350). Later 350s had different internal components than earlier ones. Head castings, intake manifold design and even the piston design all play a role.
* Intended use: A street-driven car will have vastly different requirements than a dedicated race car. A larger camshaft will improve performance at higher RPMs, but can make the engine hard to drive at low RPM, even lugging.
* Other modifications: Are you running stock heads, intake manifold, and carburetor? Modifications to these parts will influence the camshaft selection. High-compression pistons or aftermarket heads will allow for a larger cam than stock parts. Stock parts are typically less tolerant of large cams.
* "Big" is relative: What one person considers a "big" cam, another might consider mild. A cam with a duration in the .480-.510 range at .050 inch lift might be considered mild in some circles but aggressive in others, depending on the application.
General Guidelines (with HUGE caveats):
A relatively *mild* camshaft might be suitable for a stock small-block Chevy intended for street use. This could be in the .450"-.480" duration at .050" lift range. However, even this might negatively affect low-end torque and drivability.
Anything significantly larger than this, unless you've made supporting modifications (e.g., better flowing heads, upgraded intake, appropriate valve springs, etc.), will likely:
* Reduce low-end torque: Making the car sluggish at lower RPMs.
* Require significant tuning: Properly tuning a larger camshaft is crucial to ensure it runs well and doesn't damage the engine.
* Potentially lead to valve-to-piston clearance issues: A larger cam can cause the valves to hit the pistons, requiring piston reliefs or different camshaft selection.
* Impact your engine's longevity: High lift and duration put more stress on the valvetrain.
Recommendation:
Before choosing a camshaft, consult with a reputable engine builder or camshaft manufacturer. They can help you select a camshaft that's appropriate for your specific engine, intended use, and budget. Providing them with all the details of your engine and planned modifications is critical to getting a good recommendation. They will likely need to know the heads and intake you are using, what your goals are for the engine's power and drivability, and what kind of converter you are using if it is an automatic.
Simply put, there's no safe, simple answer without knowing your specific engine build and goals. Doing your research or getting professional guidance is crucial to avoid damaging your engine.
