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Pontiac 347 V8 Engine

The Pontiac 347 V8 was introduced for the 1957 model year and did quite a bit to change the future for the muscle car era. The 347 was simply a bored out version of the Pontiac 316 V8 with a longer stroke. Most notably is that the 347 had the honor of being the first engine from Pontiac to use the famous tri-power carburetor setup which consisted of 3 two barrel carburetors. The idea behind tri-power was that the middle of the three carburetors would feed the engine at cruising speeds and at idle but when more power was needed the other two carbs would open up and supply the engine with a greater amount of fuel. This idea became very popular with Pontiac and would be used up until the mid 1960s on the famous Pontiac 389.

The 347 was available in a large number of options that produced a large variety of horsepower ratings. One of the rarest 347 models every produced was a fuel injected version that was used in the Pontiac Bonneville and produced 315 horsepower. There were only 630 of these fuel injected Bonnevilles ever produced and they were all convertibles. There was also a special 347 NASCAR model built that included the tri power option as well and put out a respectable 317 horsepower. For the 1958 model year the 347 would be replaced by the Pontiac 370 V8.

 

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Engine Specifications

1957 with 2 Barrel Carb
(Lower Compression)

Max Brake Horsepower - 227 @ 4600 rpm
Max Torque - 333 @ 2300 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 8.5
Firing Order - 18436572

1957 with 2 Barrel Carb
(Higher Compression)

Max Brake Horsepower - 252 @ 4600 rpm
Max Torque - 354 @ 2400 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 10.0
Firing Order - 18436572

1957 with 4 Barrel Carb
(Lower Compression)

Max Brake Horsepower - 244 @ 4800 rpm
Max Torque - 350 @ 2600 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 8.5
Firing Order - 18436572

1957 with 4 Barrel Carb
(Higher Compression)

Max Brake Horsepower - 270 @ 4600 rpm
Max Torque - 359 @ 2800 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 10.0
Firing Order - 18436572

1957 with 4 Barrel Carb
(Even Higher Compression)

Max Brake Horsepower - 314 @ 4800 rpm
Max Torque - 375 @ 2800 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 10.25
Firing Order - 18436572

1957 with 3 X 2 Barrel Carbs
(Tri Power)

Max Brake Horsepower - 290 @ 5000 rpm
Max Torque - 375 @ 2800 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 10.0
Firing Order - 18436572

1957 with 3 X 2 Barrel Carbs
(Tri Power NASCAR)

Max Brake Horsepower - 317 @ 5200 rpm
Max Torque - 375 @ 2800 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 10.0
Firing Order - 18436572

1957 with Fuel Injection
(Bonneville Convertible)

Max Brake Horsepower - 315 @ 5000 rpm
Max Torque - 375 @ 2800 rpm
Stroke - 3.5625
Bore - 3.9375
Compression - 10.0
Firing Order - 18436572