1955-1982 Pontiac V-8 Engines – Part 1
When introduced in 1955, the Pontiac V-8 was quite modern. It grew in displacement each year through 1958.
Pontiac Small Journal V8s – Part One: 287 to 370 CID
Pontiac V8 engines are broken into two categories, small main journal and large main journal engines. All Pontiac engines have the same deck height except for the 1969 303 Trans Am engine and the short-lived 301 and 265 V8s of the early 80s.
The early 287-370 engines used smaller main journals, with the first two utilizing 2.5″ mains and the 347 and 370 using 2.623″ mains. The 389 and 400 engines used the “small” (3.00″) main journals. The last small journal V-8s, the 301 and 265 CID, versions, reverted to the original 287 CID’s 2.5″ mains.
The 421, 428, and 455 engines used the “large” (3.25) mains and were categorized as “large journal” Pontiac V8s.
The Formative Years
Significant in early Pontiac engine development was that this engine increased in size by 100 cubic inches in only 4 years! This was unheard of in the industry where 3-year cycles were the norm. But Pontiac was chasing the mid-market performance image and had started out with a relatively small displacement V8 to begin with. Thus, they needed to increase displacement each year to catch and then move ahead of their market competition. It is a testament to the original design that the engine could grow to this size with little design changes.
Engines are listed in the order of introduction by Pontiac.
Pontiac V8 engines are broken into two categories, small main journal and large main journal engines. All Pontiac engines have the same deck height except for the 1969 303 Trans Am engine and the short-lived 301 and 265 V8s of the early 80s.
The early 287-370 engines used smaller main journals, with the first two utilizing 2.5″ mains and the 347 and 370 using 2.623″ mains. The 301 and 265 reverted to the original 287’s 2.5″ mains. 389 and 400 engines used the “small” (3.00″) main journals; and the 421, 428, and 455 engines used the “large” (3.25) mains.
The Formative Years
Significant in early Pontiac engine development was that this engine increased in size by 100 cubic inches in only 4 years! This was unheard of in the industry where 3-year cycles were the norm. But Pontiac was chasing the mid-market performance image and had started out with a relatively small displacement V8 to begin with. Thus, they needed to increase displacement each year to catch and then move ahead of their market competition. It is a testament to the original design that the engine could grow to this size with little design changes.
Engines are listed in the order of introduction.
The 287 CID V8 (1955)
The engine as introduced, was an “over square” engine with a bore of 3.75″ and a stroke of 3.25″, for a total displacement of 287.2 cu in. Compression ratio was 8.00:1, with valve diameters of 1.781″ (intake) and 1.500″ (exhaust).
It was rated 180 hp @ 4600 rpm and 264 ft lbs @ 2400 rpm with a two-barrel carburetor, 200 hp @ 4600 rpm and 278 ft lbs @ 2800 rpm with the four-barrel carburetor. The 287 was a short-lived engine size, as Pontiac realized that in the introductory year, its competition had already moved to a minimum of 320 cubic inches, and a new-sized engine would be introduced next year.
1955 Pontiac 287 CID Engine Specifications
Click the tabs for specific engine information
Standard Transmission V-8: Overhead valves. Cast iron block. Five main bearings.
Displacement: 287.2 CID.
Bore and stroke: 3.750″ x 3.25″.
Compression ratio: 7.4:1.
Horsepower: 173 @ 4400.
Torque: 260 @ 2400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 264°, Exhaust 269°, Overlap 49°. Lift: 0.367″.
Carburetor: Carter WGD 2-barrel any of the following models: 2182S, 2182SA, 2182SB, 2207S or 2207SB.
Hydra-Matic Transmission V-8: Overhead valves. Cast iron block. Five main bearings.
Displacement: 287.2 CID.
Bore and stroke: 3.750″ x 3.25″.
Compression ratio: 8.0:1.
Horsepower: 180 @ 4600.
Torque: 264 @ 2400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 264°, Exhaust 269°, Overlap 49°. Lift: 0.367″.
Carburetor: Carter WGD 2-barrel with any one of the following models: 2182S, 2182SA, 2182SB, 2207S or 2207SB. NOTE: Some cars received the Rochester 2GC two-barrel.
Optional “Power Pack” V-8: Overhead valves. Cast iron block. Five main bearings.
Displacement: 287.2 CID.
Bore and stroke: 3.750″ x 3.25″.
Compression ratio: 8.0:1.
Horsepower: 200 @ 4800.
Torque: 264 @ 2600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 264°, Exhaust 269°, Overlap 49°. Lift: 0.367″.
Carburetor: Rochester 4GC four-barrel carburetor. NOTE: some Power Pack equipped cars used Carter WCFB model 2268S and 2283S four-barrel carburetors.
The 316.6 CID V8 (1956)
For 1956 the V8 was bored out to 3.9375″, increasing displacement to 316.6 cu in. Other than increased displacement, this engine was the same as the 1955 version. It was offered 2 and 4 barrel and 2-4 barrel versions, in 8.5, 7.9, 8.9 and 10.0:1 compression ratios, with hp from 192 to 285. The cylinder heads were similar and still contained 1.781″ intakes and 1.500″ exhausts.
1956 Pontiac 317 CID Engine Specifications
Click the tabs for specific engine information
- 173 HP 287 CID Economy V-8
- 192 HP 317 CID V-8
- 205 HP 317 CID V-8
- 216 HP 317 CID V-8
- 227 HP 317 CID V-8
- 285 HP 317 CID V-8
860-870 Series Economy with Manual Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 287 CID.
Bore and stroke: 3.750″ x 3.25″.
Compression ratio: 7.4:1.
Horsepower: 173 @ 4400.
Torque: 260 @ 2400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 264°, Exhaust 269°, Overlap 49°. Lift: 0.367″.
Carburetor: Carter WGD two-barrel Model 2182 S, 2182 SA, 2270S, or 2270SB.
860-870 Series Economy with Manual Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 316.6 CID.
Bore and stroke: 3.9375″ x 3.25″.
Compression ratio: 7.9:1.
Horsepower: 192 @ 4400.
Torque: 297 @ 2400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 270°, Overlap 49°, Lift 0.370″.
Carburetor: Rochester 2GC two-barrel Model 7008696.
NOTE: This engine replaced the 287 CID V-8 mid-year.
860-870 Series with Hydra-Matic Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 316.6 CID.
Bore and stroke: 3.9375″ x 3.25″.
Compression ratio: 8.9:1.
Horsepower: 205 @ 4600.
Torque: 294 @ 2600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 280°, Exhaust 280°, Overlap 55°, Lift 0.400″.
Carburetor: Rochester 2GC two-barrel Model 7008695.
Star Chief and Safari Series with Standard Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 316.6 CID.
Bore and stroke: 3.9375″ x 3.25″.
Compression ratio: 8.5:1.
Horsepower: 216 @ 4800.
Torque: 315 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 270°, Overlap 49°, Lift 0.370″.
Carburetor: Carter WCFB 2364S.
Star Chief & Safari Series with Hydra-Matic Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 316.6 CID.
Bore and stroke: 3.9375″ x 3.25″.
Compression ratio: 8.9:1.
Horsepower: 227 @ 4800.
Torque: 312 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 280°, Exhaust 280°, Overlap 55°, Lift 0.400″.
Carburetor: Carter WCFB four-barrel Model 2364S or Rochester Model 7008697.
NOTE: This engine was later optional on all 860-870 Series Chieftains, including wagons.
Optional “Extra Horsepower” V-8 – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 316.6 CID.
Bore and stroke: 3.9375″ x 3.25″.
Compression ratio: 10.0:1.
Horsepower: 285 @ 5100 RPM.
Torque: 330 @ 3600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 289°, Exhaust 298°, Overlap 71°, Intake Lift 0.409″, Exhaust Lift 0.413″.
Carburetors: Two 4-barrel Rochester carburetors Models: Front & Rear 7009820.
The 347 CID V8 (1957)
In 1957 the V8’s stroke was increased to 3.5625″ for a displacement of 347 cu in. For the first time, Pontiac offered the soon to be famous Tri-Power, three two-barrel carburetor manifold. This unit replaced the 1956 dual-quad set-up. Power increased accordingly and there were engines in the stable with horsepower from 227 to 317 and compression ratios from from 8.5:1 to 10.25. The heads ere improved with larger valves installed; 1.88″ intakes and 1.60″ exhausts. These size valves would be used for all Pontiac V8s until the introduction of the Super Duty Engines in 1961.
Several dealer-installed “NASCAR” camshafts were offered that increased power to 310 hp @ 5200 rpm, 375 ft lbs @ 2800 rpm.
Fuel Injected 347 CID V8s
Standard only for the Pontiac Bonneville was the newly introduced Rochester fuel injection system. It was similar, but not identical, to the Chevrolet unit. Pontiac did not release official power ratings for this engine, saying only that it had more than 300 hp. Contemporary tests suggest that it was actually somewhat inferior to the Tri-Power engines, although it did have better fuel economy. The was later engine was rated at 300 hp @ 5200 rpm, 375 ft lbs @ 2800 rpm. Only 630 Bonnevilles were produced with fuel-injected 347 V-8s.
1957 Pontiac 347 CID Engine Specifications
Click the tabs for specific engine information
- 227 HP 347 CID V-8
- 252 HP 347 CID V-8
- 244 HP 347 CID V-8
- 270 HP 347 CID V-8
- 290 HP 347 CID V-8
- 300 HP 347 CID Fuel Injection V-8
- 317 HP 347 CID V-8
- 317 HP 347 CID Mechanical Cam V-8
Chieftain Series with Manual Transmission. Overhead valves. Cast-iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 8.5:1.
Horsepower: 227 @ 4600.
Torque: 333 @ 2300 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 270°, Overlap 49°, Lift 0.370″.
Carburetor: Rochester 2GC two-barrel Model 7009832.
Chieftain Series with Hydra-Matic Transmission. Overhead valves. Cast-iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 8.5:1.
Horsepower: 252 @ 4600.
Torque: 354 @ 2400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake – 269°, Exhaust 280°, Overlap 55°, Lift 0.400″.
Carburetor: Rochester 2GC two-barrel Model 7009831.
Super Chief, Star Chief and Safari Series with Standard Transmission. Overhead valves. Cast-iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 8.5:1.
Horsepower: 244 @ 4800.
Torque: 338 @ 2700 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 270°, Overlap 49°, Lift 0.370″.
Carburetor: Rochester four-barrel Model 7009829.
Super Chief, Star Chief & Safari Series with Hydra-Matic Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 10.0:1.
Horsepower: 270 @ 4800.
Torque: 359 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 280°, Overlap 55°, Lift 0.400″.
Carburetor: Carter AFB four-barrel Model 2506S or Rochester Model 7009830.
Optional “Extra Horsepower” V-8 – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 10.0:1.
Horsepower: 290 @ 5000 RPM.
Torque: 356 @ 3200 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 280°, Overlap 55°, Lift 0.370″.
Carburetors: Three 2-barrel Rochester carburetors Models: (Front) 7011351 (Center) 7011350 (Rear) 7011352.
“Extra Horsepower” Fuel Injection – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 10.25:1.
Horsepower: 300 @ 5200 RPM.
Torque: 375 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 280°, Overlap 55°, Lift 0.370″.
Induction: Rochester mechanical fuel-injection Model 7014880.
NOTE 1: The factory hesitated to release the horsepower for this engine, however it later admitted to “300”.
NOTE 2: This fuel injection unit was the same in principle as the the Chevrolet unit, but a specific design created by Rochester for the Pontiac engine.
Optional “Extra Horsepower” V-8 – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 10.0:1.
Horsepower: 317 @ 5200 RPM.
Torque: 356 @ 3200 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 283°, Exhaust 293°, Overlap 60°, Lift 0.411″.
Carburetors: Three 2-barrel Rochester carburetors Models: (Hydra-Matic) Front 7011351, Center 7011350, Rear 7011352. (Synchromesh) Front 7011902, Center 7011903, Rear 7011904.
Optional “Extra Horsepower” V-8 – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 347 CID.
Bore and stroke: 3.9375″ x 3.5625″.
Compression ratio: 10.0:1.
Horsepower: 317 @ 5200 RPM.
Torque: 356 @ 3200 RPM.
Valve lifters: Mechanical.
Camshaft timing: Intake 270°, Exhaust 270°, Overlap 58°, Lift 0.435″. Tappet Clearance 0.023″.
Carburetors: Three 2-barrel Rochester carburetors Models: (Hydra-Matic) Front 7011351, Center 7011350, Rear 7011352. (Synchromesh) Front 7011902, Center 7011903, Rear 7011904.
Ignition: Dual-breaker.
The 370 CID V8 (1958)
For 1958, the V8’s bore was increased again to 4.0625″, increasing displacement to 369.4 cu in. The engine is now called the “Tempest V-8” and would be called this through1960. The increase in displacement resulted in increase hp and torque, with power ratings from 240 to 330 and torque ratings from 330 to 415. Compression was again up, with the base at 8.6:1 and the top engines at 10.5:1.
The fuel-injected engine was now an option on the Bonneville, with a price tag of $500 which for the day was almost 15% of the car’s base price. It was rated at 310 hp @ 4800 rpm and 400 ft lbs @ 3,000 rpm with 10.5:1 compression. Performance engines began with the 285 hp 4 barrel engine and included the 300 hp Tri-Power, the 310 hp Fuel Injection, and two “NASCAR” engines, the 315 hp 4-barrel and the 330 HP Tri-Power. Only about 400 of the 1958 fuel injection engines were produced before the system was quietly dropped.
1958 Pontiac 370 CID Engine Specifications
Click the tabs for specific engine information
- 240 HP 370 CID V-8
- 255 HP 370 CID V-8 SMT
- 255 HP 370 CID V-8 AMT
- 285 HP 370 CID V-8
- 300 HP 370 CID V-8
- 310 HP 370 CID Fuel Injection V-8
- 315 HP 370 CID V-8
- 330 HP 330 CID V-8
Chieftain & Super Chief Series with Manual Transmission. Overhead valves. Cast-iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 8.6:1.
Horsepower: 240 @ 4500.
Torque: 354 @ 2600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 270°, Overlap 49°, Lift 0.370″.
Carburetor: Rochester 2GC two-barrel Model 7012703.
Bonneville, Star Chief & Safari Series with Manual Transmission. Overhead valves. Cast-iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 8.6:1.
Horsepower: 255 @ 4500.
Torque: 360 @ 2600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 269°, Exhaust 270°, Overlap 49°, Lift 0.370″.
Carburetor: Carter AFB four-barrel Model 2768S.
Chieftain & Super Chief Series with Hydra-Matic Transmission. Overhead valves. Cast-iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 8.6:1.
Horsepower: 255 @ 4500.
Torque: 360 @ 2600 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake – 273°, Exhaust 282°, Overlap 55°, Lift 0.400″.
Carburetor: Carter AFB four-barrel Model 2740S.
Bonneville, Star Chief & Safari Series with Hydra-Matic Transmission. Overhead valves. Cast iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 10.0:1.
Horsepower: 285 @ 4600.
Torque: 395 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 273°, Exhaust 282°, Overlap 55°, Lift 0.400″.
Carburetor: Carter AFB four-barrel Model 2740S.
Optional “Extra Horsepower” V-8 – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 10.5:1.
Horsepower: 300 @ 4600 RPM.
Torque: 3400 @ 3000 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 273°, Exhaust 282°, Overlap 55°, Lift 0.400″.
Carburetors: Three 2-barrel Rochester carburetors Models: Front (all) 7011705 Center (manual trans) 7011709 (Hydra-Matic) 7011706 Rear (all) 7011707.
“Extra Horsepower” Fuel Injection – Available All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 10.5:1.
Horsepower: 310 @ 4800 RPM.
Torque: 400 @ 3400 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 273°, Exhaust 282°, Overlap 55°, Lift 0.400″.
Induction: Rochester mechanical fuel-injection Model 7014880.
NOTE: This fuel injection unit was the same in principle as the the Chevrolet unit, but a specific design created by Rochester for the Pontiac engine.
“Extra Horsepower Tempest 395-A” V-8 – Available on All Models. Overhead valves. Cast iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 10.5:1.
Horsepower: 315 @ 5000 RPM.
Torque: 400 @ 2800 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 283°, Exhaust 293°, Overlap 60°, Lift 0.411″.
Carburetor: Carter AFB Model (manual trans) 2768S (Hydra-Matic trans) 2767S.
Exhaust: Low-restriction dual exhausts,
Ignition: Dual-breaker.
“Extra Horsepower Tempest 395-A” V-8 – Available 2-door Sedans & Hardtops Only. Overhead valves. Cast iron block. Five main bearings.
Displacement: 370 CID.
Bore and stroke: 4.0625″ x 3.5625″.
Compression ratio: 10.5:1.
Horsepower: 330 @ 5200 RPM.
Torque: 415 @ 3000 RPM.
Valve lifters: Hydraulic.
Camshaft timing: Intake 283°, Exhaust 293°, Overlap 60°, Lift 0.411″.
Carburetors: Three 2-barrel Rochester carburetors Models: Front (all) 7011705, Center (manual trans) 7011709, (Hydra-Matic) 7011706, Rear (all) 7011707.
Exhaust: Low-restriction dual exhausts,
Ignition: dual-breaker.