How to Get Power Out of a 305 Chevy

by Chris Orr
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The 305-cubic-inch small block Chevrolet engine was designed to power a wide range of vehicles from the 1970s through the 1990's including the Chevy Camaro. While the Chevy 305 engine is considered under powered by hot rod enthusiasts, many companies provide after market parts to increase the horsepower of this engine. Some improvements come from parts that can be added to the engine. Other improvements require that the engine be removed from the car and rebuilt.

Bolt-on Upgrades

Step 1

Replace the exhaust manifold. The stock exhaust manifold of the 305 engine restricts air flow from the engine increasing back pressure. Back pressure is the the result of something obstructing the flow of air causing air to build up behind the obstruction and increasing pressure. This back pressure results in exhaust gases contaminating the fresh fuel air mixture in the combustion chamber reducing horsepower. Headers or other aftermarket exhaust manifolds designed for the Chevy 305 increase the flow of exhaust gases which decreases back pressure and increases the power of the engine.

Step 2

Replace the intake manifold and carburetor. Aftermarket intake manifolds designed for the Chevy 305 increase and smooth out the flow of air and fuel to the engine. A larger carburetor for the Chevy 305 also increases the flow air into the engine. The reduction in air resistance and turbulence ensures the efficient delivery of the fuel/air charge to the cylinders and better horse power.

Step 3

Add cold air induction. Standard induction systems with paper air filters again restrict the flow of air to the engine. Cold air induction systems reduce resistance and temperature of the air provided to the engine increasing horse power. An effective system will produce a cold air intake for the Chevy 305 that improves the flow of cool air to the engine. Its filters reduce the dust and other particles that create wear on the engine parts.

Step 4

Replace the computer chip. Newer cars with computer controlled electronic ignition systems see a horsepower increase with special aftermarket computer chips. These chip are designed to alter the performance profile of the car in favor of additional horsepower. Some computer chips for different Chevy cars with the 305 cubic inch engine offer gains of up to 75 horsepower.

Rebuilding the Engine to Increase Horsepower.

Step 1

Bore and hone the cylinders. Rebuilding an engine to increase horsepower is a major undertaking. It requires the removal of the engine from the vehicle and stripping it down to the core. Boring and honing each cylinder and replacing the pistons and rings increases the displacement of the engine and restores lost compression from worn rings and age. An automotive machine shop with a cylinder boring machine is required.

Step 2

Replace the camshaft. Depending on the requirements of the owner, aftermarket camshafts can increase power and the lower end or the upper end of the engine's RPM range.

Step 3

Port and polish the heads. In the same way as an aftermarket intake manifold , porting and polishing each valve seat increases the flow of air into and out of the engine by eliminating restrictions. It also provides a smoother and better fitting seat for each valve, preventing leaks when the valve is closed.

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