Mopar Engine Specs
Intro
Mopar engine specs need to be sorted by family before the numbers mean much. A Mopar 318, 383, 426, or 440 can point to different hardware, different eras, and different parts rules depending on the engine family.
Use this page to get into the right Mopar engine family first. Then use the family page and individual displacement pages to confirm the actual engine, production range, bore, stroke, firing order, variants, and compatibility notes.
The family comes before the displacement. That rule keeps an A-series poly 318 from getting treated like an LA 318, keeps a 426 wedge from getting sold as a 426 Hemi, and keeps B-series and RB-series big blocks from being shoved into one lazy Mopar parts bucket.
↑ Back to the Top, Before the Family Tree Gets Another Branch
Big Blocks
Gen I Chrysler Hemi – 1951 – 1958
The Gen I Chrysler Hemi family covers the early Chrysler 331, 354, and 392 Hemi engines before the later 426 made the Hemi name famous again. It matters because early Chrysler, Dodge, DeSoto, Gen II, and modern Hemi engines are separate parts conversations.
Engines covered: 331, 354, 392
B-Series Big-Block – 1958- 1978
The B-series big-block was Mopar’s low-deck big-block family and one of the core classic Mopar V8 groups. It includes common performance and passenger-car engines, but it needs to be separated from the taller-deck RB family before parts assumptions start.
Engines covered: 350, 361, 383, 400
RB-Series Big-Block – 1959- 1979
The RB-series was Mopar’s raised-block big-block family, used for larger displacement and heavier-duty performance work. It includes the 413, 426 wedge, and 440, which are related to the B-series but not identical in the details that matter.
Engines covered: 413, 426 wedge, 440
Gen II 426 Hemi – 1964- 1971
The Gen II Hemi is the muscle-era 426 Hemi family, not the same thing as the earlier Chrysler Gen I Hemi engines, Dodge early Hemis, DeSoto early Hemis, or modern Gen III Hemi engines. It is the famous race-bred Mopar Hemi line, and the proof burden is high because the name attracts stories fast.
Engines covered: 426
Small Blocks
A-Series Poly Small-Block – 1956-1967
The A-series Poly family was Mopar’s early small-block branch before the LA small-block became the long-running mainstream line. It matters because the Poly engines share some family history with later small blocks, but the heads, layout, and parts assumptions are not the same.
Engines covered: 277, 301, 303, 313, 318, 326
LA Small-Block – 1964 – 2003
The LA family became Mopar’s main small-block V8 line for classic street, performance, truck, and later Magnum-era development. It includes the familiar 273, 318, 340, and 360, but displacement alone still does not identify the version.
Engines covered: 273, 318, 340, 360
Parting Shot
Start with the Mopar engine family, then move to the displacement page. The family tells you which parts rules, identification clues, and compatibility limits belong to the engine in front of you.
A Mopar displacement number by itself is only a clue. The family page is where the number gets context, and the individual engine page is where the details start proving or killing the story.