Plymouth A Specs: 3.91 x 3.31 in

Plymouth A specs: 3.91 x 3.31 in (99.3 x 84.1 mm) bore and stroke, shared by all 2 versions. Displacement, compression and factory ratings, plus rod ratio.

At a glance

Displacement	318 ci
Cylinders	8
Bore	3.910"
Stroke	3.310"
Advertised power	230–290 hp
Years	1957–1966

Engines in this family

Engine	Displacement	Bore × Stroke	CR	HP
A 318 (poly)	318 ci	3.91" × 3.31"	—	—
A (1957–1966)	318 ci	3.91" × 3.31"	—	230–290

Factory cars with a A

• Plymouth Fury: 1957, 290 hp; 1958, 290 hp; 1959, 230 hp; 1959, 260 hp; 1960, 230 hp; 1960, 260 hp; 1961, 230 hp; 1961, 260 hp; 1962, 230 hp; 1962, 260 hp; 1963, 230 hp; 1964, 230 hp; 1965, 230 hp; 1966, 230 hp
• Plymouth Satellite: 1965, 230 hp; 1966, 230 hp

What varies across the family

All are oversquare — bore larger than stroke, which favours revs over low-end torque.

Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.

← All Plymouth engines