Plymouth LA Engine Specs

Bore, stroke, displacement and compression for all 20 Plymouth LA engines, compared side by side. Plus rod ratio and head specs where published.

At a glance

Displacement273–360 ci
Cylinders8
Bore3.630–4.039"
Stroke3.311–3.579"
Compression8.4–10.5:1
Advertised power120–290 hp
Years1960–2000

Engines in this family

EngineDisplacementBore × StrokeCRHP
K360 ci4.0315" × 3.5787"8.4:1245
360 LA V8360 ci4" × 3.5787"8.4:1245
J340 ci4.0315" × 3.311"10.5:1275–290
340 LA V8340 ci4.0394" × 3.311"10.5:1275
H340 ci4.0315" × 3.311"—240–275
J340 ci4.0315" × 3.311"—290
340 4-bbl340 ci4.0315" × 3.311"—240–275
LA (1968–1973)340 ci4.0315" × 3.311"—240–290
318318 ci3.9094" × 3.311"9.2:1260
LM318 ci3.9094" × 3.311"9:1230
G318 ci3.9094" × 3.311"—150–230
318 2-bbl318 ci3.9094" × 3.311"—145–230
LA 318 2-bbl318 ci3.9094" × 3.311"—230
LA (1960–1980)318 ci3.9094" × 3.311"—120–260
Magnum 5.2318 ci3.9094" × 3.311"—230
LA 318318 ci3.9094" × 3.311"—150
A273 ci3.6299" × 3.311"10.5:1235
A273 ci3.6299" × 3.311"8.8:1180
LA (1964–1969)273 ci3.6299" × 3.311"—180–235
sales code 699273 ci3.6299" × 3.311"—275

Factory cars with a LA

What varies across the family

Both bore and stroke vary across the family, so these are separate castings rather than variations on one block.

Compression spans 8.4:1 to 10.5:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.

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