Cars by name
Trucks and Jeeps

Engines / Trans
Repairs / Fixes
Tests and Reviews

Dodge Warlock

Buying AMC / Jeep

AMC V8 Engines

By Mike Sealey

AMC VIN decoding
Brazilian Kaiser/Willys/Jeep engines

American Motors' first family of homegrown V8s is not well known to most enthusiasts, and there is a great deal of confusion about their origins. Those who are lucky enough to have made their acquaintance know them to have more than enough power for daily driver duty, with a sweet power curve, a willingness to cruise all day at 70-80 mph, and surprising fuel economy — or maybe not so surprising, considering the manufacturer.

amc 360

The story starts in the early 1950s, not with Nash-Kelvinator or Hudson, but up the road from Detroit at Kaiser-Frazer in Willow Run, Michigan. It would be an understatement to say that Kaiser-Frazer was run differently from other car companies. They had plenty of automotive talent, with former Chrysler and Willys-Overland executive Joseph W. Frazer and the cadre of talented engineers and designers he recruited. Frazer, at the time, was CEO of Graham-Paige, which had not built cars since the 1941 Graham, but had managed to stay in business with defense contracts and the manufacture of Rototillers, a now generic term which was originally the brand name of a Graham-Paige invention.

These were countered by Henry J. Kaiser and his long-time associates, who had been enormously successful in construction, mining and shipbuilding, and felt certain their energy and enthusiasm would create similar success in the car business.

AMC 327 engine

Kaiser and his people were defined by a kind of “can-do" optimism which was a part of every project they tackled. (Henry J. Kaiser’s personal philosophy could be neatly summarized by his famous saying, “Find A Need And Fill It!,” which took on a tongue-in-cheek meaning when it appeared on Kaiser cement trucks in the 1960s.)

While this may have worked well when taking on and filling government construction contracts in nominally unrelated industries, it translated into a scattergun approach with automobiles, which are ultimately one of the higher priced discretionary consumer purchases. While Kaiser was incredibly successful where “prettification” of the product was concerned - their Art and Colour department, under Carleton Spencer, did more to get auto upholstery out of the mohair era than any one other manufacturer - they were less successful in mechanical upgrades.

Other than small improvements of the type that most people never see or notice, the final 1955 Kaiser Manhattans only differed mechanically from the 226 flathead 6 in the initial 1946 models in two major ways: optional GM Hydra-Matic, offered from 1951 on, and the McCulloch supercharger (later known as a Paxton supercharger) seen on 1954 and 1955 Manhattans. The supercharger was seen as a desperate attempt to stay in the horsepower race without a V8 engine.

While Kaiser never succeeded in getting a more modern engine into passenger car production, it wasn’t for lack of experimentation. A 1951 Kaiser Jade Dragon which started life as Henry J. Kaiser's personal car still exists with the experimental 248 ci overhead cam six that was built and tested in this car. How much relationship if any exists between this engine and the 230 ci OHC 6 used in Jeep Wagoneers in the 1960s is not known.

At another point, Kaiser tried to buy the Oldsmobile "Rocket" 303 V8 for use in Manhattans. Legend has it that Olds was ready to sell engines to K-F, but changed its mind when it saw how fast the lighter Kaiser was with the hot Olds engine!


Kaiser also played with an experimental V8 of its own design, a 288 ci unit primarily created by K-F powertrain engineer David Potter. At some point K-F decided it did not have the money to build this engine. At somewhere close to the same point in time (not sure of the exact chronology), David Potter left K-F for a job at AMC, or perhaps one of its parent companies. When interviewed about the K-F V8 in the 1970s, Potter was vague about whether he brought the design with him or just did something similar from scratch, but surviving pictures of the K-F 288 show an engine that appears identical to the first-generation AMC V8. (And this engine did eventually make its way into Kaiser-built vehicles. We'll get back to that shortly.)

The early 1950s were difficult years for America's independent auto manufacturers. While the biggest problem was most likely Henry Ford II glutting the market with new cars in a vain effort to catch and pass Chevrolet, one of the lesser problems was the market's embrace of the V8 engine, which required tooling changes beyond the capacity of most smaller automakers. Studebaker was the only independent to come out with a V8 prior to 1955, and even this great little engine was designed before anyone realized what a big deal the horsepower race was going to be, with only limited room for expansion.

Nash-Kelvinator CEO George Mason saw this need looming on the horizon and started talking with the other independent automakers about pooling resources. N-K started by acquiring Hudson, which created American Motors. Packard, which had a V8 of its own well on the way to production, countered by buying Studebaker, only to find out after the purchase that Studebaker had a break-even point of 271,000 cars per year, a number that had not been reached since 1950.

Historians on both sides say that Mason's next plan was to incorporate Studebaker-Packard into AMC, which would have given the combined company four makes of big car plus the successful Rambler and Metropolitan, plus two distinct families of V8 engine to choose from depending on size and power requirements. This plan fell apart after George Mason's unexpected death in late 1954.

AMC and S-P went ahead with their first tentative plans toward merger, which would have been agreed upon while Mason was still alive, and which involved offering the smaller Clipper version of the new Packard V8 in 1955 Nash Ambassadors and the new Nash-bodied Hudson Hornets. Packard also provided its Twin Ultramatic automatic transmission for use with its V8.

When Mason's successor, George Romney, took over at AMC, he looked at the merger proposal and decided against going further, proposing instead "love without marriage." Instead, the relationship between the two companies turned ugly, with S-P contending that AMC never offered them anything they could not get from another vendor for less money and AMC responding that the Packard engine contract had them paying too much for V8s and Ultramatics, which in turn forced them to price cars with this combination at a higher price than buyers were willing to pay.

The discovery that one of AMC’s new hires had just designed an excellent V8 engine for Kaiser-Frazer could not have been more timely. It is said that George Romney, a devout Mormon, considered this a gift from God. The speed of the new AMC V8’s development suggests that the Kaiser work was accepted as what would normally have been AMC’s preproduction process. It also suggests that AMC jumped on David Potter's V8 quite literally as soon as they became aware of its existence.

The first edition of this engine, at 250 cubic inches (4.1 liters), appeared halfway through the 1956 model year in Nash Ambassador Special and Hudson Hornet Special models. The Specials were not only a lower trim level than the Packard-powered Ambassadors and Hornets, which remained in production, but were seven inches shorter! This was because the AMC V8 went into what had been the shorter Nash Statesman/Hudson Wasp platform, which had been powered by Nash and Hudson sixes respectively up to that time. The new V8 also used a GM Hydramatic transmission instead of the troublesome Packard Twin Ultramatic. (AMC had continued to use Hydramatics behind its sixes, as indeed both Nash and Hudson had done before their merger.)

Today, George Romney is best remembered for calling the typical fullsize 1950s American car a "gas-guzzling dinosaur." Most have forgotten that he was saying this even as AMC was sill producing small numbers of fullsize Nashes and Hudsons... in fairness to Romney, he was known to add "... and we make them, too..." during the early AMC years. And even more have forgotten that the 1956 Rambler went through the same longer-lower-wider restyle everyone else was doing in the industry. Actually, that had to have started under George Mason, since the first step toward a larger Rambler was the 1954 introduction of four-door sedans and wagons on a 108" wheelbase, as compared to the 100inch wheelbase the two-door models had used since their introduction in 1950.

The major 1956 restyle, which Romney pushed forward a year from the original 1957 plan, made the Rambler into a much larger and more physically impressive car, losing the two-door models and concentrating 100% on the 108" wheelbase with new models including a four-door hardtop and the industry's first four-door hardtop station wagon. (The 100inch wheelbase models would return as the 1958 Rambler American, but that's a story for another time.)

Noted AMC historian Patrick Foster tells us Romney took Rambler in this direction because he felt the need to compete in the Chevy-Ford-Plymouth price range with models similar to what the competition was selling. This, too, was the rationale for the Rambler V8, which came out in 1957 models and surprised most observers outside

AMC. Although the 250 V8 got a sneak preview in the Ambassador Special and Hudson Special of 1956, it was meant from the beginning as the Rambler V8. It was the smallest passenger car V8 on the market in 1957, but its smaller size was not a handicap at all in the smaller Rambler, especially with its standard dual exhaust. Horsepower output in 2 barrel configuration was a more-than-respectable 190, the same rating as Ford's entry-level 272 and higher than the first two V8s on Chevy's 1957 option list.

As was the practice for the Rambler Six, Rambler V8s were offered in midrange "Super" and highline "Custom" trim (the sixes were also offered in an entry-level "Deluxe" trim level not open to V8s). The four-door hardtop was only offered in Super trim as a 6, and only in Custom trim as a V8, and the four-door hardtop wagon was only offered as a Custom V8.

The 1957 Nash Ambassador and Hudson Hornet lost their Packard engine and transmission, but gained a larger version of the new AMC V8. This had an inch larger bore than the 250 for a displacement of 327 cubic inches... five years before the Chevy V8 of the same size that many confused folks think powered AMC products.

The cover of the 1957 Hudson brochure announced "Power's Up - Price's Down", and both claims were true. The big 1957 AMCs sold for less since AMC no longer had to pay Packard's price for engines. And the 327 had 255 horsepower, a higher number than the previous year's Packard V8 despite the Packard unit having 25 more cubic inches. (One of the points of contention between the two companies was Packard's insistence that Hudson and Nash engines produce less horsepower than the virtually identical engine used in Clippers. This was accomplished on the cheap by use of thick head gaskets, which in fact were so thick that they lowered the compression ratio on AMC-bound engines, and with that the horsepower rating.) All these games went out the window as AMC retook its own destiny with its own engines. (Early 1957s used GM Hydramatics, while a switch to Borg-Warner automatics seems to have taken place somewhere in the middle of the model year.)

The biggest surprise took place in December of 1956, when AMC introduced the awesome Rambler Rebel, which combined the 327 from the big cars with the smaller body of the Rambler four-door hardtop. Rebel 327s differed from the Ambassador/Hornet 327s by virtue of mechanical valve lifters and a higher compression ratio. (Both engines were rated at 255 hp... it's suspected that the Rebel was slightly underrated, perhaps to make the stillborn fuel-injection option appear to be more of an improvement.)

The Rebel was a real screamer - Motor Trend magazine said the only 1957 model they tested that beat the Rebel's 0-60 mph time was the Corvette with the fuel-injected 283. Even the mighty Chrysler 300C came in a tenth of a second behind the Rebel in 0-60 time. And even more was planned than that!

The 1957 Rebel was supposed to offer an optional Bendix "Electrojector" electronic fuel injection system, which was said to produce 288 horsepower, and which Motor Trend believed would have proven even faster than the fuelie Corvette had it made production. (The Electrojector was not quite ready for prime time, AMC ultimately passing on it due to chronic issues with cold-weather starting. Chrysler offered it as an option on its hotter 1958 models, but the problems were nowhere near resolved and most of the EFI MoPars were recalled and retrofitted with dual quads. Bendix eventually sold its Electrojector patents to Germany's Robert Bosch GmbH, who as the years went by eventually worked out the bugs in numerous European applications, and ultimately brought it back to the US for successful use in the '75 Cadillac Seville.)

The 1958-60 Rebel did not reach the same heights as the original, but were still desirable and powerful cars. Basically, the "Rebel" name went on all 108 inch wheelbase Rambler V8 models in those years. Foster describes these as a cross between the previous V8 Ramblers, in that they offered more power than the original Rambler V8, but less than the 1957 Rebel. All 1958s and 1959s had the 250 engine with a 4 barrel carb and dual exhaust, and were rated at 215 hp and 260 lb/ft of torque.

I owned a 1959 Rebel Custom station wagon in the 1970s with this engine and the pushbutton Borg-Warner automatic AMC used from 1958 through 1962, and was absolutely convinced this engine was a 327 until I read up on it. It was that powerful. I owned a 1959 Ford Country Sedan station wagon at about the same time, probably the most popular wagon in America that year, with the optional 352 2 barrel and two-speed Fordomatic. The Ford was no slouch but the (admittedly lighter) Rambler gave absolutely nothing away to it in performance despite having nearly 100 less cubic inches.

In 1960, the 4 barrel 250 was joined briefly by a 2 barrel version rated at 200 hp. The Rebel did not return for 1961, and neither did the 250. The volume Rambler model was renamed the "Classic" for 1961, and was only sold in six-cylinder form. (The Classic got a V8 and the Rebel made its return before the end of our story. We'll get back to that.)

The real 327 was restricted to the "Ambassador by Rambler", a more luxurious longer wheelbase version (117") of the Rambler built to replace the big Nash and Hudson models. The long wheelbase variation continued through 1961, after which it was superceded by the 108inch wheelbase Rambler Ambassador, formalizing the model name most people had used to refer to the bigger car. The 1962 Ambassador continued using the 327 and a higher level of trim, especially in its "Ambassador 400" version, despite losing its exclusive wheelbase.

During this time, and most likely in later years as well, Gray Marine marketed modified 250s and 327s for boat use. I discovered this when a boat-owning friend called saying his boat supposedly had a 327, but it didn't look like any Chevy V8 he had ever seen (sigh). Apparently one of Gray Marine's modifications involved the installation of a reverse-rotation camshaft, since prop rotation needs to go counterclockwise, unlike a driveshaft. So, if you run into one of these, some parts will interchange but others won't - proceed with caution.

In 1962, George Romney ran for governor of Michigan and won. The presidency of AMC was filled by former sales manager Roy Abernethy, who had come to American Motors from Kaiser-Willys, and who had started his sales career at Packard. It would be fair to say that Abernethy did not share Romney's belief in smaller cars. Strangely enough, his desire to focus on larger Ramblers was accompanied by an ad campaign noted for its open hostility toward high performance, solidifying the public's growing mistaken belief that Ramblers were slow cars primarily for older folks. The mixed messages which defined Abernethy's tenure confused buyers, and sales plummeted. Some of his moves played a part in later developments of this family of V8 engine.

1963 was noted for the first all-new Rambler body in years, a clean design by outgoing AMC design chief Ed Anderson. With the new bodies came "Tri-Poised Power', a revised system of engine mounting. This is a big deal today because 1963 and later V8s will not interchange with 1962 and earlier due to different engine mounts.

1963 was also the year the Classic got a V8 again. This was 287 cubic inches, very close to the 288 the engine displaced as a Kaiser prototype. As time went by, the 287 joined the 327 as an Ambassador engine, while the 327 became available in Classics. By 1965, when the Ambassador (once again on a longer wheelbase, and now with a unique front and rear end appearance) became available with the new 232 ci Six, marketing was thoroughly confused and the separate identities that had served AMC so well during the Romney years were thoroughly muddled.

232 six

Probably the most notorious example of this was the Marlin, which started out life as a cute American-based showcar called the Tarpon. The Tarpon was a big hit, and Abernethy approved it for production... but insisted on doing it on the Classic platform so three people could fit in the back seat. The proportions did not translate well from the smaller car to the larger one, and the Marlin was an enormous flop at a time when AMC could ill afford one.

The AMC 327 did find an important new market in 1965, appearing for the first time in Kaiser's Jeep Wagoneer sport-utility and Gladiator pickup in a "homecoming" of sorts. The 327 Jeep was a gutsy vehicle and was very well received.

327 engine

The Rebel name reappeared on a dressy two-door hardtop version of the Classic in 1966, and the "Rambler" name was removed from the Ambassador and Marlin at the same time. By this time, the writing was on the wall; a new thinwall-casting 290 ci V8 had been developed for the Rambler Rogue, an upscale variation of the Rambler American two-door hardtop and convertible created to compete with the Nova SS, Valiant Signet and Dart GT.

Rambler got into V8 compacts much later than the competition, in part because the 287/327 was too big to shoehorn in there. By 1967, the 290 and closely related 343 were the only V8s in AMC passenger cars, followed in 1968 by the 390, which was also built using the new block as its basis. In later years, the 290 became the 304, the 343 became the 360, and the 390 became the 401. The old 327 soldiered on a couple of years longer in Jeeps before being replaced in 1969 by the Buick 350 - which was itself replaced after AMC's takeover of Jeep by the newer AMC V8s.

The International Harvester Travelall used the AMC 401 engine in 1974-75, during a shortage of IH 392.

Note: According to Chilton’s, Jeeps with 258 cubic inch straight-six engines used a Carter BBD carburetor from the 1979 to 1986 model years. The AMC 360 V8 engines in those years used a Motorcraft 2150 2-barrel carburetor — some say that was trouble-prone. The 304 appears to have used the Motorcraft 2100 2-barrel for 1979 and 1980. A Rochester 2SE (E2SE in California) was on the four-cylinder engines for the 1981 and 1982 models, and on the disreputable GM 2.8-liter V6 during the 1985 and 1986 model years (likely also in 1984 Cherokees); from 1983-86, AMC reportedly switched to the Carter YFA.

AMC history | Hudson | Nash-Kelvinator | Torqueflite (used by AMC) | Mopar engines

Wrangler prototypes spotted on Rubicon?

Pritchett sets record in cooler temps at Brainerd

Clarifying: JL 4×4 vs 4WD

More Mopar Car
and Truck News