AMC V-8s

{{Note1}} Portions of the following text came from [http://www.wps.com/AMC/Rambler-327/The%20New%20American%20Motors%20V-8%20Engine%20%28SAE%20Paper%20details%29.htm The New American Motors V-8 Engine] by John F. Adamson, Carl E. Burke and David B. Potter of the American Motors Corp. This paper was first presented at the SAE National Passenger-Car, Body and Materials Meeting, Detroit, Michigan, March 7, 1956.  

AMC made their own V-8 engines. The company did use a few parts from other manufacturers, namely transmissions, carburetors, and electrical systems (distributor, alternator/generator, starter, etc.). Many people see a similar displacement (327, 390, etc.) engine with a Delco (GM) or Autolite (Ford) ignition/starting/charging system on it and assume the engine was purchased from GM or Ford. Anyone familiar with GM and Ford V-8s would immediately know they were looking at a different engine at first glance though.  

AMC only purchased one V-8 from another manufacturer. That was the Packard 320 cid V-8 for the big 1955 Nash Ambassador and Hudson Hornet models, and the Packard 352 cid V-8 for the 1956 full-size Nash Ambassador and Hudson Hornet. These were equipped only with the Packard Ultramatic automatic transmission. AMC and Packard were supposed to have had a "gentleman's agreement" to cross purchase parts. This was partially to establish a working relationship between the two companies for a possible future merger. As it turned out, Packard felt it was doing AMC a favor by selling AMC V-8s. Packard sent a few bids in to AMC, but they were rejected for being too high- even though AMC was paying a premium for the Packard V-8s.  

Needless to say, this incensed AMC management. George Mason, head of AMC, ordered his engineers to get him a V-8 as soon as possible. Just 18 months after receiving the order, AMC introduced a 250 cid V-8 in mid 1956. It was only used in the Nash Ambassador Special and Hudson Hornet Special. The Specials were really two door Statesman/Wasp models with Ambassador/Hornet trim. The Statesman/Wasp bodies were built on a shorter wheelbase and lighter than the bigger cars. Using that platform helped improve the little 195-hp 250 cid V-8's power-to weight ratio.  

18 months from drawing board to production doesn't sound all that short today, but in the era of slide rules and drafting boards (no computer modeling or even calculators!) it was phenomenal. One of the ways the AMC Engineering Department worked this miracle was to hire David Potter from Kaiser-Frazer. He had previously worked with Continental Engines (owned by Kaiser Industries) on a 288 cid V-8 intended for the Kaiser-Frazer line, however Kaiser had since purchased Willys-Overland resulting in a change of its priorities; from making cars, to making the more popular Jeeps. AMC literature reports that "The entire program was under the direction of Meade F. Moore, Vice-President of Automotive Research and Engineering, and through his efforts the project was carried on cooperatively by our Kenosha and Detroit Engineering Departments. Obviously, such a division of both design and development required the utmost in teamwork by F. F. Kishline, Chief Engineer, and his assistants, E. L. Monson and J. S. Voigt in Kenosha, and by R. H. Isbrandt, Chief Design Engineer, and W. S. Berry, Chief Mechanical Engineer, in Detroit." AMC concluded in their announcement of the new engine saying "In short, our objective was an engine with maximum flexibility with regard to future displacement requirements without sacrificing any of the performance features of the power-plant. Economy of operation and manufacturing processes, along with excellent weight and durability characteristics, were all part of our aims. We think that we have succeeded in reaching these objectives, and have produced an engine that is second to none. It is an engine of which we are justly proud."

==Engine design==

The Rambler V8 design features a visually identical 'Hudson X' crankcase gallery, having the main bearing webbing form an 'X' around the main bearings transferring load from the the crankshaft into the block with extreme stiffness and minimized vibration for maximum durability. The Rambler V8 shaft mounted rocker arm assemblies are visually identical to the the former Nash inline six cylinder engines. The engine features an excellent oil system, which is perhaps the best oil system of any US V8 ever made and serves as a model of oil system design theory for it's attributes.

All 250 models use solid lifters, the 287/327s are hydraulic. These engines were also used by Grey Marine for boats in the late '50s and early to mid '60s. All the marine engines used solid lifters regardless of size.

The AMC Rambler V8 has only recently been labeled 'Gen 1' by newer AMC enthusiasts. This labeling was first used by AMC writer Frank Swygert (aka editor/forum member 'farna') in an effort to place the engine where it technically "should" be. Technically the labeling is correct; this is the first generation of AMC V-8s, AMC having been formed in May of 1954 and V-8 engine development starting in 1955. The 1966-'69 second generation models and 1970-'91 third generation models are very similar, but having a different block and head casting led to the labeling of Gen-2 and Gen-3. "Series" could have been used instead of "Generation", but "Generation" (shortened to "Gen") seemed to be the most correct description. Previously the first generation AMC V-8 had been (and still is) referred to as either the "Nash V-8" or "Rambler V-8". It was used in both Nash and Rambler branded, as well as AMC branded cars ("Rambler" was dropped from the 1965 Marlin and 1966 Ambassador, those being branded as AMC models). Technically it was built by the American Motors Corporation, not Nash or Rambler.

AMC made some improvements in the Gen-2 design for 1970, thus becoming the Gen 3. This resulted in different block and head castings and slightly larger displacement. The only change to the block was adding approximately 1/16" to the deck height and increasing the stroke accordingly.

The Gen 1 to Gen 2 block deck height difference was 1/32" nominal, or 0.033". Gen 1 was 9.175" nominal block deck height and Gen 2 was 9.208" nominal block deck height per the Performance American Style booklet AMC printed in the early '70's.

The 290 became a 304, 343 a 360, and the 390 a 401 (with a little added stroke in the crank than the 390). The 401 wasn't introduced until 1971. The 390 was kept for 1970 only by using a special piston; the pin height was altered to keep displacement at 390 inches. The head casting was changed to create a slightly larger "dog leg" exhaust port (Gen-2 heads have rectangular exhaust ports) to improve exhaust flow.  

The AMC V-8 finally went out of production when Chrysler halted Jeep Grand Wagoneer production at the end of the 1991 model year. This makes the 360 by far the most numerous AMC V-8. It can easily be built to produce over 400 hp on pump gas. It's as modern as any other make V-8 of the time, and has as much potential. There isn't as large a selection of performance parts, but the parts still available are the ones known to work well. The parts cost a little more than the more common small block Ford and Chevy parts, but no more than any other make. Cost to build is partially offset by the very good heads. Until the Vortec L31 5.7L head was introduced, Chevy heads weren't any better than AMC heads. Now, Edelbrock has aluminum heads for the 343, 360, 390 and 401 AMC engines.

| bgcolor="#ffffff"| ||align = "center" |1957||align = "center" |EFI'''*'''||288 @ ????||align = "center" |N/A||align = "center"|1957 Rebel engineering prototypes only

| bgcolor="#ffffff"| ||align = "center" |1957||align = "center" |4V||255 @ ????||align = "center" |N/A  

'''<nowiki>*</nowiki>'''Bendix Electrojector. AMC decided it wasn't reliable enough at the last minute and pulled it as an available option. Sources vary on the number built, only two can be verified; they showed up at Daytona Speed week in late 1956 where manufacturers were showcasing their new products. An Electrojector-equipped 1957 Rebel was the second fastest car in Daytona from 0-60 mph. It was beat only by a Rochester FI Corvette. It easily outpaced larger Hemi powered (354 and 392 cid) cars, but it must be pointed out that those engines were also in larger, heavier cars (a 1957 Nash Rebel weighed around 3400 pounds, a Chrysler 300C weighed 5000 pounds).

The 4V intake will bolt to the 287, which had no factory 4V option. The intake carb pattern is standard Holley, and because the 4150C used is only in the 450-500 cfm range (about right for the 250), it's easy to bolt a much more reasonably sized 600-650 cfm carb on the 287/327.  

There are no intakes made, though I have seen a rare three deuce intake once, I think it was made by Fenton, but not sure. Whereas the Rambler V8 intake manifold is a 'free-standing' design with a separate lifter valley cover, AMC Gen-2 intakes can be adapted by cutting to remove the water and exhaust crossovers and fabricating 1/4" spacer/adapter plates for each side. The ports aren't an exact match, but can be matched with the 1/4" plate. A small block Chevy intake can also be adapted, but the V angles are different and the adapter plates must match angle also. The ports aren't an exact match, but can be matched with the 1/4" plate. A small block Chevy intake can also be adapted, but the V angles are different and the adapter plates must match angle also.  

The first AMC V8 engine became widely known as 'Rambler V8', and was also labeled by AMC as 'Ambassador V8' (327cid) in those models. The second all new design AMC V8 debuted in 1966 with 290 cid, then a 343 cid version in 1967 and a 390 cid version in 1968. AMC raised the deck height of their second V8 engine design in 1970, stroking the 290 to 304 cid, the 343 to 360 cid and made a new connecting rod for the 390 version. Along with the raised deck, AMC increased the head bolt size from 1/2" to 7/16" and redesigned the rectangular exhaust ports to have a raised port floor with an enlargement of the outlet beside the port floor underneath one of the exhaust flange bolts (called the 'dog leg' exhaust port to differentiate it from the rectangular port heads). The second design V8 engine has good interchangeability due to sharing the same basic architecture. The first AMC V8 engine also has near total interchangeability between the 250, 287 and 327 cid versions; only the pistons do not because cid differences were made with bore size change only.

At first glance, the Rambler V8 (also renamed 'Gen 1') looks much like the Studebaker V8; they both have similar sized rounded top large valve covers attached to the block with two large wing-nuts, a rear mounted distributor, a dual plane free standing intake manifold, a tin valley cover and a front-of-block 'free standing' water outlet manifold having the thermostat and outlet for the upper radiator hose going to the radiator. The Rambler V8 looks physically big primarily because of the large valve covers, and that the exhaust ports continue out to the edge of the block before they terminate to the exhaust manifolds. (Pontiac V8 and Ford 'FE' V8 exhaust ports have a similar design).  

**1956-'62:

The 327 was used in the 1957 Rambler Rebel, the 1957 Nash and Hudson big cars (no Ramblers) and all 1958-'64 Rambler Ambassadors. It was also available in the 1965-'66 Marlin and Ambassador. All 1957-'59 327 cid engines have Holley 4150c or Carter WCFB 4V carbs and 9.0:1 to 9.7:1 compression depending on application, as do all 1960-'66 4V models. The 1960-'66 base 327 has a Holley 2V carb and 8.7:1 compression. All 4V models also had dual exhaust. The carburetor is rather small at 450-500 cfm, which limits power somewhat.  

The 250 was only used in the mid-1956 Nash/Hudson Specials, 1957 Rambler V-8 (other than the Rebel), and 1958-'61 Rambler Rebel models (I know, it can be confusing, but all V-8 Ramblers used the Rebel nameplate 1958-'61). Base 2V models have Carter WCD 2V carbs and 8.7:1 compression. All 4V models use a Holley 4150C carb with 8.7:1 compression and dual exhaust.

AMC used GM hydramatic transmissions in 1957 switching later to a Borg-Warner automatic transmission behind their Gen-1 engine. Only manual transmissions were used in the 1956 Specials. AMC called the GM automatic "Flashaway" and the Borg-Warner transmission "Flash-O-Matic". It's a three speed cast iron case Borg-Warner Model 8 with a vacuum modulator valve. The column shift quadrant will read P-R-N-2-D-1-L. The 1 and 2 are small.  

1965-'66 models used a throttle valve cable instead of a vacuum modulator to control internal pressure. This is the M-10, internally similar to the M-8 except for the TV cable and valve body. The cable '''must''' be connected for the transmission to work correctly! Otherwise it will burn up like a cable equipped GM TH700R4 or a Chrysler transmission without the "kick-down" linkage connected. An electric solenoid inside the valve body controls kick-down (passing gear). A switch on the throttle linkage (usually on the engine) is activated at wide open throttle to force a downshift for passing, etc. It will not kick down over a certain speed, usually in the 60-70 mph range.  

 

 

Parts are available from several old auto trans sources. [www.nwtparts.com Northwest Transmission], Fatsco (www.fatsco.com), and Dave Edwards (www.autotran.us) are good sources.  

Kaiser Jeeps used a TH400 in the Wagoneer and pickup from 1963-'67. It's the "universal" TH400, which was the Buick Nailhead model. Buick Nailhead engines have a deep flange on the back of the block covering the flexplate/flywheel which require a shallower bellhousing than other GM engines. That shallow bellhousing left room to make an adapter without adding length to the engine/trans, so GM sold it as a "universal" model and continued production a few years after the Nailhead bit the dust. If you get one make sure you get the 1-1/2" to 2" thick cast iron adapter as well as the flexplate and spacer. The crank will need a pilot bushing to match the flexplate. As stated, a Nailhead TH400 will work if you get just the adapter. Rolls-Royce and Jaguar used the universal TH400, among other smaller makers who didn't need enough units to warrant casting a new case. If using another AMC sourced transmission behind a former Jeep 327 with auto, make sure the thin pilot bushing is removed first.

The AMC Gen 1 V-8 has a unique bellhousing pattern. 1955 AMC built Nash and Hudson models and all but the 1956 Nash/Hudson Specials used a Packard V-8.  The "Specials" were the shorter wheelbase/lighter weight Nash Statesman and Hornet Wasp two-door bodies with Ambassador/Hornet trim to make it easier on the 250/4V V-8, and to distinguish them from the Packard-powered big cars. AMC had a purchase agreement with Packard for V8s and auto transmissions in 1955-'56. Packard was supposed to buy some parts from AMC but didn't, so AMC got ticked off and started making their own V8.  

The AMC Gen 2 290 cid V-8 appeared in late 1966 in the American, and across the board as a 290 or 343 cid engine in 1967. The Gen 2 engines use a different bolt pattern than the Gen 1. Pre-1972 inline sixes use a smaller diameter bellhousing than the Gen 2/3 V8s) with a bolt pattern shared only with the small 1950-'54 Nash L-head sixes. All 1972 and later AMC inline sixes and V-8s use the same Gen 2/3 V8 bellhousing bolt pattern.