Pontiac 389 V8 Engine

The Pontiac 389 V8 was first introduced in 1959 and would become one of the most popular engines of the muscle car era. The engine evolved from the Pontiac 370 in which the stroke was increased. There were a lot of changes to the 389 during its eight year production run which gained the engine even more notoriety. Most experts agree that the 389 was one of the key factors in starting the muscle car wars of the 60s.

One of the first major changes for the 389 came in 1960 when Pontiac stopped using its “reverse flow” cooling option for the powerful V8. From 1955 to 1959, Pontiac had used a cooling system (and some GM motors still use it today) where the coolant was sent to the heads first and then down through the block. The idea behind “reverse flow” was to keep the heads cooler because of the large problem with engines in the 50s burning up and warping the valves. By 1960 GM had started using harder and more reliable valves and seats for their engine heads which let them do away with the “reverse flow” cooling method. For more information on “reverse flow” and why Pontiac stopped using it check out this interesting site.

The 389 was also the first engine by Pontiac to come with the S.D. (Super Duty) option. If you are lucky enough to find a 389 S.D. engine then you will have quite an impressive setup such as a four bolt main engine block and a forged steel crankshaft and connecting rods. These Super Duty 389 engines were mainly used for NASCAR racing but a small amount of them offered for sale to the public in order to meet NASCAR standards.

Another impressive version of the 389 introduced in 1959 was the Tempest model. The Tempest 389 engines were also known as “420-A” motors and came with higher compression as well as better performance options. These engines were available up through 1962 and produced up to 348 horsepower which was the highest power output a factory 389 engine would ever see with the Tri-Power carb setup.

The 389 Pontiac motor also has the coveted award as being the first engine used in one of the most famous muscle cars of all times, the Pontiac GTO. The GTO is considered by many automotive enthusiasts to be first real muscle car on the block even though it’s a discussion that could be debated. By the end of 1966 the last of 389 engines rolled off the assembly line to be replaced by the Pontiac 400 but it didn’t leave without leaving a lasting legacy on the automotive world that will never be forgotten.

Problems Associated with the 389

The OEM cam timing gear from the factory was nylon coated and the coating would become hard and flake off at around 30k to 40k miles. The flaking of the nylon was a slow process and as the pieces came off they were ground up in the timing chain which would then cause them to pass into the oil and clog up the oil pump pick that in turn would deprive the engine of oil. After this destructive process took its toll over a long period of time, the engine, without warning, would seize up or it would destroy the rod bearings and main bearings. In either scenario, the lower part of the engine would no longer function which resulted in mandatory replacement of the crankshaft, oil pump, rod and main bearings. In some instances, if the bearing spun in the rods or block, it was necessary to replace the block and/or rods.

Engine Specifications

1959 - 1963 with 2 Barrel Carb (Econo Model)

Max Brake Horsepower: 215 @ 3600 rpm
Max Torque: 390 @ 2000 rpm
Stroke: 3.750
Bore: 4.0625
Compression: 8.6
Firing Order: 18436572

1959 with 2 Barrel Carb (Straight Drive Transmission)

Max Brake Horsepower: 245 @ 4200 rpm
Max Torque: 392 @ 2000 rpm
Stroke: 3.75
Bore: 4.0625
Compression: 8.6
Firing Order: 18436572

1959 - 1964 with 4 Barrel Carb (Straight Drive Transmission)

Max Brake Horsepower: 260 @ 4200 rpm - 59, 281 @ 4400 rpm - 60, 235 @ 3600 rpm - 61-64
Max Torque: 400 @ 2800 rpm - 59, 413 @ 2800 rpm - 60, 402 @ 2000 rpm - 61-63, 386 @ 2000 rpm - 64
Stroke: 3.75
Bore: 4.0625
Compression: 8.6
Firing Order: 18436572

1959 - 1962 with 2 Barrel Carb (Automatic Transmission)

Max Brake Horsepower: 280 @ 4400 rpm - 59, 283 @ 3600 rpm 60-62
Max Torque: 408 @ 2800 rpm - 59, 413 @ 2800 rpm - 60-62
Stroke: 3.75
Bore: 4.0625
Compression: 10.0 - 59, 10.25 - 60-62
Firing Order: 18436572

1961 - 1966 with 2 Barrel Carb (Low Compression With Automatic Trans.) (Engine Code - 04L,05L,08R,09R for 61-64) (Engine Code - WA,WB,YA,YB for 65-66)

Max Brake Horsepower: 230 @ 4000 rpm - 61-64, 256 @ 4600 rpm - 65-66
Max Torque: 380 @ 2000 rpm - 61-63, 386 @ 2000 rpm - 64, 388 @ 2400 rpm - 65-66
Stroke: 3.75
Bore: 4.0625
Compression: 8.6
Firing Order: 18436572

1963 - 1964 with 4 Barrel Carb (High Compression With Straightdrive Trans.) (Engine Code - 10A)

Max Brake Horsepower: 283 @ 3600 rpm
Max Torque: 413 @ 2800 rpm - 63, 418 @ 2800 rpm - 64
Stroke: 3.75
Bore: 4.0625
Compression: 10.25 - 63, 10.5 - 64
Firing Order: 18436572

1961 - 1964 with 2 Barrel Carb (High Compression With Automatic Trans.) (Engine Code - 11H or 12H)

Max Brake Horsepower: 267 @ 4200 rpm - 61-64, 283 @ 3600 rpm - 61-62
Max Torque: 405 @ 2400 rpm - 61-63, 413 @ 2800 rpm - 61-62, 410 @ 2800 rpm - 64
Stroke: 3.75
Bore: 4.0625
Compression: 10.25
Firing Order: 18436572

1959 - 1964 with 4 Barrel Carb (High Compression With Automatic Trans.) (Engine Code - 25K,26K,27P,28P)

Max Brake Horsepower: 300 @ 4600 rpm - 59, 303 @ 4600 rpm - 60-64
Max Torque: 420 @ 2800 rpm - 59, 425 @ 2800 rpm - 60-63, 430 @ 2800 rpm - 64
Stroke: 3.75
Bore: 4.0625
Compression: 10.0 - 59, 10.25 - 60-63, 10.5 - 64
Firing Order: 18436572

1964 with 4 Barrel Carb (Engine Code 23B or 29N)

Max Brake Horsepower: 306 @ 4600 rpm
Max Torque: 420 @ 3200 rpm
Stroke: 3.750
Bore: 4.0625
Compression: 10.5
Firing Order: 18436572

1959 - 1963 with 3 x 2 Barrel Carbs (Tri-Power Option)

Max Brake Horsepower: 315 @ 4600 rpm - 59, 318 @ 4600 rpm - 60-62, 313 @ 4600 rpm - 63
Max Torque: 425 @ 3200 rpm - 59, 430 @ 3200 rpm - 60-63
Stroke: 3.75
Bore: 4.0625
Compression: 10.5 - 59, 10.75 - 60-62, 10.25 - 63
Firing Order: 18436572

1959 - 62 with 4 Barrel Carb (420-A Tempest Model)

Max Brake Horsepower: 330 @ 4800 rpm - 59, 333 @ 4800 rpm - 60-62
Max Torque: 420 @ 2800 rpm - 59, 425 @ 2800 rpm - 60-62
Stroke: 3.75
Bore: 4.0625
Compression: 10.5 - 59, 10.75 - 60-62
Firing Order: 18436572

1959 - 1962 with 3 X 2 Barrel Carbs (420-A Tri-Power Tempest Model) (Engine Code 76X or 77J)

Max Brake Horsepower: 345 @ 4800 rpm - 59, 348 @ 4800 rpm - 60-62
Max Torque: 425 @ 3200 rpm - 59, 430 @ 3200 rpm - 60-62
Stroke: 3.75
Bore: 4.0625
Compression: 10.5 - 59, 10.75 - 60-62
Firing Order: 18436572

1965 - 1966 with 4 Barrel Carb (Depends on the Engine Code Number)

Max Brake Horsepower: 325 @ 5200 rpm - 78X or 79J, 333 @ 5000 rpm - WE, 335 @ 5000 rpm - WT or YS
Max Torque: 429 @ 2800 rpm - 78X or 79J, 429 @ 3200 rpm - WE, 431 @ 3200 rpm - WT or YS
Stroke: 3.75
Bore: 4.0625
Compression: 10.5
Firing Order: 18436572

1965 - 1966 with 3 x 2 Barrel Carbs (Tri-Power Option)

Max Brake Horsepower: 360 @ 5200 rpm
Max Torque: 424 @ 3600 rpm
Stroke: 3.75
Bore: 4.0625
Compression: 10.75
Firing Order: 18436572
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