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