The Chevy 350 is a very simple and inexpensive motor to build and to add horsepower to. As a consequence, this motor is found in applications from hot rods and sports cars to boats and trucks. No matter what application your Chevy 350 motor is in, a few simple steps can get you more better performance and higher horsepower.
Modify your air intake. This can be done in a variety of ways, from simply installing a K & N air filter to installing a complete cold-air-intake system. A cold-air-intake system, also offered by K&N, will gain the most horsepower, but is the most expensive. The more cool air your motor can take in, the more horsepower it can generate, so choose the intake modifications you make based on what horsepower gains you desire.
Modify your exhaust. Once you have increased air intake, you must give the engine a place for that air to go. Exhaust options include a dual exhaust, headers and increases in pipe diameter up to 3 inches. Headers are scientifically designed exhaust manifolds that produce the proper back pressure for your motor, while allowing it to "exhale" more efficiently. More expensive headers do a better job of increasing horsepower, and are of higher quality. A dual exhaust is considered the most efficient for horsepower gain, but for aesthetic reasons, sometimes a single exhaust system can be designed to provide adequate horsepower gain without detracting from the appearance of a hot rod.
Change your camshafts and valve train. From cams with more lift and duration, to roller rocker arms and hydraulic lifters, increasing horsepower through valve train modifications is relatively inexpensive. However, some camshafts decrease the drivability of your Chevy 350 as a street vehicle. Typically, anything above what is known as an RV cam is too radical for street use, and considered a racing cam. Roller rockers and hydraulic lifters increase horsepower by decreasing resistance in the valve train. These modifications require a minimum amount of engine disassembly, and can enhance performance significantly.
Purchase new cylinder heads, or have yours ported and polished. There are several different companies offering different cylinder head configurations to enhance performance and horsepower. These improve fuel and airflow through bigger valves and specifically designed intake and exhaust ports. Often, these heads are aluminium instead of cast iron, and so reduce engine weight as well. A machine shop can rebuild your heads, and polish the ports as well. This may not produce as much horsepower gain as new heads, but it is generally less expensive.
Have your motor rebuilt and blueprinted. Blueprinting a motor involves math calculations to make sure that the crank, camshafts, pistons and cylinders all meet exact specifications. A rebuilt motor or one from a factory that you purchased is allowed a certain amount of error in these areas. If it is not exact, it still is shipped, and considered to meet factory specifications. A blueprinted motor has a smaller margin for error. Exact specifications are demanded, and thus the motor runs better and produces more horsepower. At this point, the motor could be bored out for more volume, and the crankshaft can be changed. These steps will result in significant horsepower gain.
The more modifications you do to increase horsepower in your engine, the less reliable it becomes as for daily driving up to a point. There will be constant tuning and modifications to be done. Once the motor is blueprinted, it can be very reliable. Many modifications may make it difficult for your vehicle to pass emissions standards, so if you are in a state where emissions testing is required, use caution and investigate local laws before making modifications to a vehicle you intend to drive regularly.