Engineered on a strict budget, the AMC Gen 2 and Gen 3 V8s powered AMC and Jeep vehicles from 1966 through 1991, well into the Chrysler era.

1970 AMC Rebel Machine 390 CID V8 340 hp 

According to a few sources, American Motors produced one family of V8s from 1956 on, even though the automaker introduced a completely new V8 in 1966. That’s because the new V8 was built on the 4.75-inch cylinder-bore centers of the ’56 original. (See our feature on the original Rambler V8 here.) This allowed AMC to produce the new V8 on its existing tooling, saving the cash-starved automaker millions of dollars. But in fact, virtually everything else in the engine was reengineered, as only the timing chain and drive sprocket interchanged with the old V8. The ’66-forward engine is generally referred to as the Gen 2 V8, rightly so.

With the new V8, the distributor and oil pump were moved from the rear of the camshaft to the front in an aluminum housing, which also carried the water pump. Using up-to-date thinwall techniques and a reduced 9.165-in deck height, the cylinder block and head castings were reenginered to reduce size, weight, and cost. The smaller and lighter V8 (540 lbs) made its debut at mid-season of 1966 in the sporty Rambler Rogue. The previous V8 had been considered too large and heavy for the compact Rambler American platform.

In its initial form with a 3.75-in bore and 3.28-in stroke, the ’66 V8 displaced 290 cubic inches. For 1967, a 343 CID version (4.08 x 3.28) and in mid-1968, the 390 CID V8 (4.165 x 3.574) were added, all on the same basic architecture, though the 390 boasted a stiffer block and a forged crankshaft and connected rods rather than cast. In 1970, the 290 and 343 V8s were enlarged to 304 and 360 CID, respectively, with a slightly longer 3.440-in stroke and taller deck height, while in 1971 the 390 grew into the 401 using the same method.

With their taller cylinder decks (9.165-in vs. to 9.208-in) and improved cylinder heads with dogleg exhaust ports for increased airflow, the 304 CID, 360 CID, and 401 CID engines are known as Gen 3 V8s. Arguably, the pinnacle of AMC V8 peformance, in quasi-factory form anyway, was the Gen 2 390 CID V8 used in the Hurst-prepared ’69 AMX Super Stock drag cars. This specially tuned V8 (below) sported Crane-modified heads, an Edelbrock crossram intake manifold, and 12.3: compression ratio, and in dyno testing it produced more than 520 hp. Meanwhile, the standard Gen 3 V8 carried on in various AMC road cars for years to come, including the Jeep Grand Wagoneer where, in 360 CID form, it remained in production through 1991—well into the Chrysler years.