How to Build a High Performance 350 Engine
Without question, the 350 is General Motor's most popular small-block engine, both for street and high-performance applications. First produced in 1968, the 350 featured a surprising amount of power for its size. However, the 350 can be made to produce substantially more power than it did from the factory. The key to building horsepower with the 350 is improving its restrictive stock fuel delivery and exhaust systems. Parts selection is critical, so always consult the various manufacturers to determine which type of component is best for the engine's intended purpose.
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Things You'll Need
- Aftermarket aluminum cylinder heads
- Aftermarket aluminum intake manifold
- Aftermarket carburetor
- Exhaust headers
- Dual exhaust system
Instructions
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Replace the cylinder heads with aluminum aftermarket heads. Within the cylinder heads are the valves, which are partially responsible for directing air and fuel into the combustion chambers. The 350's stock valve sizes are relatively small and therefore restrictive. Aftermarket heads feature larger valves, which allow a greater quantity of air and fuel to reach the combustion chambers, which increase the engine's power output. Aluminum aftermarket heads are also substantially lighter than the 350's stock cast iron heads, which reduces the weight of the vehicle, thereby making it quicker.
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Replace the intake manifold with an aluminum aftermarket unit. The 350's stock intake manifold has the same deficiency as do the stock cylinder heads. Before the air and fuel mixture reaches the cylinder heads, that mixture must first flow through the eight passages within the intake manifold. The stock passages are smaller than the passages in aftermarket manifolds. Replacing the manifold will allow the cylinder heads to receive the additional air and fuel they need. The aluminum design will also reduce the weight of the vehicle.
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Replace the carburetor with one that flows more air and fuel. With the replacement cylinder heads and intake manifold ready for a greater quantity of air and fuel, it is necessary to replace the stock carburetor with a unit that can produce a larger quantity of air and fuel. Carburetors are rated in cubic feet per minute, or "cfm" for short. The higher the cfm number, the more air and fuel the carburetor can produce. The biggest mistake when selecting a carburetor is choosing one which produces more air and fuel than the engine can handle, so always discuss the purpose for which the engine will be used with the carburetor company to determine which carburetor is best for the application.
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Replace the stock exhaust manifolds and exhaust pipes with headers and a dual exhaust system. With the aftermarket cylinder heads, intake manifold and carburetor, the engine is now producing more power and burning more fuel. As a consequence, the engine is now also producing more exhaust. If the exhaust fumes are not routed away from the engine fast enough, the engine's power output will suffer. Therefore, replace the restrictive stock exhaust manifolds with exhaust headers, and install a dual exhaust system, which will quickly carry the fumes away from the vehicle.
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