The 454 big-block Chevy was introduced in 1970 and has been used in family sedans, performance muscle cars, pickups, motor homes and race cars. It's a versatile engine that produces great amounts of torque. When highly modified, it is also capable of producing horsepower figures approaching 1000 or more. Selecting a camshaft for this engine requires some thought and careful considerations. Replacing a camshaft is a one-day task for a few experienced people (automotive technicians), and a weekend project for most others. There is no "one size fits all" choice, so it needs to be the correct choice the first time.
Decide how the vehicle is to be used. A competition engine will need a much different camshaft than a street-type high-performance engine. Race engines are designed to operate under wide-open throttle conditions almost all, if not all, of the time. Idle quality is not a concern. Street-type high-performance engines will require a cam design that would not be suitable for a stop-and-go tow-truck type vehicle, either.
Take note of all of the vehicle specifications. Establish the weight of the car (curb weight, plus driver) under conditions it will be driven in most of the time. Find out what the gear ratio of the rear axle is, along with the tire diameter being used. This determines the rpm at which the engine will be operating at highway speeds. If the car has power brakes, this needs to be considered -- cams that are too big can make power brakes ineffective.
Make note, also, of the engine specifications, and whether any modifications have been made, or are being planned. Camshaft selection is very dependent on 1) displacement, compression ratio and fuel type, 2) piston-to-valve clearance, and 3) cylinder head and induction system airflow, among other things.
Identify the stall speed of the torque converter if using an automatic transmission. Some performance oriented camshafts require increased stall speed to avoid being sluggish and unresponsive at low speeds. A manual transmission doesn't require this consideration.
Contact a camshaft manufacturer's technical help-line and provide them with all details about the car, the engine/transmission and -- most importantly -- the intended use.
Be candid. The most important thing is to be completely honest about all information, and how the car will be used. A cam that is designed for operation between 3500- and 6500-rpm will not be well suited for an engine that rarely sees the high side of 5000-rpm. If given two similar camshafts choices, select the one that appears to be less aggressive.
