1955-1982 Pontiac Small Journal and Large Journal V8s

The Pontiac V-8 remained in continuous production through 1981. Its horsepower ranged from under 200 to 370 and its engine size went from 287 all the way to 455 CID.
Shown here is a cutaway of the original 287 CID “Strato-Streak V-8”

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.

NOTE: There is no such thing as a “small” or “big” block Pontiac. All blocks are the same external size, the differences being main journal size and lower end strengthening or, later, lightening. As such, Pontiac did not have the customary “small-block” and “big-block” engine families common to other GM divisions, Ford, and Chrysler. Effectively, Pontiac’s V-8s were all small blocks, sharing the same connecting rod length 6.625 inches. The exception was the later short deck 301 CID and and 265 CID produced in the late 1970s and early 1980s. Even so, except for the lower deck height, the block configuration and external dimensions were the same. All Pontiac V-8s were phased out in 1981.

The early 287 -370 CID engines used smaller main journals, with the first two utilizing 2.5″ mains and the 347 CID and 370 CID using 2.623″ mains. The short deck 301 CID and 265 CID of the 1980s reverted to the original 287’s 2.5″ mains. The 389 CID and 400 CID engines used “small” (3.00″) main journals. The 421 CID, 428 CID, and 455 CID engines used  “large” (3.25″) mains.

Click the following image links to reach the extensive descriptions of each series of V-8s.

Pontiac Small Journal V8s – Part One   287 to 370 CID V–8s

Pontiac Small Journal V8s – Part Two   326, 389 and 400 CID V–8s

Pontiac Small Journal V8s – Part Three   326, 350, 400 & 455 CID V-8s

Pontiac Large Journal V8s   421, 428, and 455 CID V-8s