Editing AMC V-8s

{{Youcanedit}} [[File:Amc v8.jpg|right|420px]] <br><br><br> ==Overview== The AMC V8 has a [http://www.crankshaftcoalition.com/wiki/Talk:AMC_V-8s storied] history. Read about the pros and cons of both AMC V8 engines. This article will touch on the highlights. {{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. ==In the beginning== From mid-1956 on, 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. ==The Packard/AMC connection== AMC only purchased one brand of 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. AMC also discovered later that Packard was installing two head gaskets per side in the V8s they sold AMC, resulting in lower compression and less horsepower in the Packard-powered Hudson Hornets and Nash Ambassadors than the comparable Packard models. 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 initially was only used in the Nash Ambassador Special and Hudson Hornet Special. The Specials were really Statesman/Wasp models with Ambassador/Hornet trim, and they were only available as 4-door sedans and 2-door hardtops. The Statesman/Wasp bodies were built on a shorter wheelbase [114.25" vs. 121.25"] and lighter [3265 lbs. vs. 3495 lbs., curb weight] than the bigger cars. Using that platform helped improve the little 190-hp 250 cid V-8's power-to-weight ratio. Eighteen 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." The new-for-1956 640 lb. Rambler V8 (fully assembled 'long block') was lighter at that time than all other US V8 engines, except for the 1955 Chevrolet 'small block'. And when speaking about their intake and exhaust port designs, AMC reported that "the theoretical gas velocity through the valve is lower than that of any automotive engine on the market today" & "Exceptionally close liaison was maintained with our manufacturing personnel during the design and development stages of the engine". As a result, many economies in fabricating and tooling processes were built into the original design and have since been carried through into production. Tooling facilities for the V-8 are completely new, and are based on what we call "segmented automation." In this type of manufacturing, each basic section of tooling, although completely automatic, is not fully integrated with other sections. For our purposes, this type of tooling means increased flexibility as each portion of the line can be utilized independently of other operations. Of particular interest is the cylinder block boring equipment, which has been designed to finish simultaneously blocks of two different bore dimensions. It contains two sets of roughing, finishing, and chamfering tools, and blocks of either bore size can enter the equipment in any mixed sequence. Each station is set to tool one size bore, and when a block enters that station, a probe automatically determines whether or not to cycle the cutting heads. Wherefore it may be said that not only was the Rambler V8 'state-of-the-art', AMC set a new standard of excellence for the US industry. ==Engine design (Gen-1 AMC V-8, also called Nash V-8 and Rambler V-8)== American Motor's first '56-'67 Rambler V8 design features a tall 9.98" deck height with an obvious 'Hudson X' styled crankcase gallery. Having the main bearing webs form an 'X' around the main bearings transfers load from the the crankshaft into the block with extreme stiffness and minimized vibration for maximum durability. Only the 4bbl 327 CID versions feature 'solid mains'. All other versions feature 'windowed' main webs for weight reduction. The Rambler V8s feature shaft mounted rocker arm assemblies which 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 all it's attributes. There were three sizes of AMC Gen-1 V-8s: *1956-'61 250 *1963-'66 287 *1957-'67 327 (the 327, named 'Vigilante V8' was used one more year in Jeep Corporation Wagoneer and Gladiator vehicles) All these feature the same 3.25" stroke forged steel crankshaft and 6.375" forged steel connecting rods and were internally balanced from the factory. The 1963-up AMC (non-Kaiser Jeep corp.) versions all came equipped with revised/improved high-flow exhaust manifolds, although AMC did not change their advertised rating of 4bbl 327 from it's former rating of 270hp. The three CID versions were made by increasing bore diameter; The 250 made with a 3.50" bore, the 287 with 3.75" bore and the 327 a 4.00" bore. All three CID variations can be confidently bored 0.125" oversize since the stock factory cylinder walls are approximately .25" thick. Rambler V8 327 engines have been successfully bored and stroked to 418, and another to 443 CID, with no known durability issues. All 250 engines were made having solid lifters and adjustable rocker arms. All 287 and most 327 versions came with self adjusting hydraulic lifters. These engines were also used by Grey Marine for boats in the late '50s through the mid '60s. All the marine engines used solid lifters regardless of size. The easily removed 'two wingnut' style valve covers imply original solid lifter design. AM's first V8 was called 'Rambler V8' in all the old automotive literature. The alpha-numeric 'Gen-1,2,3' names were never used in any American Motors publication. 'Gen-1', 'Gen-2', etc. labeling ideas were first used by Chevrolet small block V-8 enthusiasts to distinguish the differences among that group of very similar engines. This has apparently led many to believe the terms were "borrowed" from the GM engine family or that a GM enthusiast created the labels. There was a small effort to distinguish between GM and AMC labels: GM models are typically labeled with all capitals (GEN-1, GEN-2, etc., sometimes with no dash), whereas Frank used a single capital (Gen-1, and always a dash). The label was used because it is technically correct and fits. GM's labeling wasn't even considered until others pointed out the similarities, and made the assumption that the labeling was "borrowed". ==The Gen-2 V8== By the mid '60s the heavy Gen-1 V-8 was becoming dated. AMC engineers didn't rest once the Gen-1 was introduced though. They had been working on a thoroughly modern light weight V-8 to replace the Gen-1. The Gen-2 engine was introduced in mid year 1966 as a 290cid V8. The only thing it shares with the Gen-1 is the bore spacing. This was done so that existing boring tooling could still be used. Everything else about the Gen-2 was totally unique and new, even the bell housing bolt pattern was changed. These engines are similar to a small block, but have a larger bore spacing similar to a big block. Many people call them a "mid block", but it's just the AMC Gen-2 V-8; AMC only made one V-8 design at any given time. The Gen-2 came in three sizes also: *1966-'69 290 *1967-'69 343 *1968-'69 390 The 290 and 343 used cast cranks and rods. The 390 was intended for high performance and was made with a forged crank and forged rods. AMC stated that the primary reason forgings were used was to get the engine to market quicker; they didn't have time to thoroughly test cast components and still introduce the engine when they desired to. As a result, the AMC Gen-2 390 has a tougher bottom end than any similar displacement MOPAR, Ford or Chevy engine. Reworked AMC 390 rods are good to 7000+ rpm, whereas the other makes require replacement performance rods. A lot of work also went into development of the head. AMC heads were some of the best flowing heads on the market at the time. A typical AMC head flowed as good as or better than other makes high performance heads. ==The Gen 3 V8== AMC made some improvements in the '66-'69 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 crankshaft stroke accordingly. The Gen 2 to Gen 3 block deck height difference was 1/32" nominal, or 0.033". Gen 2 was 9.175" nominal block deck height and Gen 3 was 9.208" nominal block deck height according to the factory high performance modifications book named "''Performance American Style''" published some time in the early '70s by American Motors. As a result, the short deck 290 became a 304, 343 a 360, and the 390 became a taller deck 401 CID engine. The 401 wasn't introduced until 1971. Using the new taller deck block, "AMX 390" engine displacement remained the same by using 'one year only' connecting rods and pistons. The head casting was revised to create a slightly larger "dog leg" exhaust port to improve exhaust flow. So there were four Gen-3 sizes: *1970-'79 304 *1970-'91 360 *1970 only 390 *1971-'79 401 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 a higher performance custom engine is partially offset by the very good heads. Currently, Edelbrock and Indy Cylinder Head make aluminum heads for all 343-up CID '66-'91 AM V8 engines. ==Factory power ratings== {|border="1" cellpadding="2" cellspacing="0" !bgcolor="#DDDFFF"|Size||bgcolor="#DDDFFF"|Years ||bgcolor="#DDDFFF"|Carb Type ||bgcolor="#DDDFFF"|HP @ RPM||bgcolor="#DDDFFF"|Torque @ RPM |- |bgcolor="#FFF8DC" align = "center"|'''250'''||1956-'57||align = "center" |2V||190 @ 4900||align = "center" |240 @ 2500 |- bgcolor="#F1F1F1" | bgcolor="#ffffff"| ||1958-'61||align = "center" |4V||215 @ 4900||align = "center" |260 @ 2500 |- | bgcolor="#ffffff"| ||1960-'61||align = "center" |2V||200 @ 4900||align = "center" |245 @ 2500 |- |- bgcolor="#F1F1F1" |bgcolor="#FFF8DC" align = "center"|'''287'''||1963-'66||align = "center" |2V||198 @ 4700||align = "center" |280 @ 2600 |- |bgcolor="#FFF8DC" align = "center"|'''327'''||1957||align = "center" |EFI'''*'''||288 @ ????||align = "center" |N/A||align = "center"|1957 Rebel engineering prototypes only |- | bgcolor="#ffffff"| || |1957||align = "center" |4V||255 @ ????||align = "center" |N/A |- bgcolor="#F1F1F1" | bgcolor="#ffffff"| ||1958-'66||align = "center" |4V||270 @ 4700||align = "center" |360 @ 2600||&nbsp;With dual exhaust |- | bgcolor="#ffffff"| ||1958-'66||align = "center" |2V||250 @ 4900||align = "center" |340 @ 2600 |} '''<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 February 1957 where manufacturers were showcasing their new products. An Electrojector-equipped 1957 Rebel was the second fastest car in Daytona from 0-60 mph. At 7.2 seconds, it was beaten only by a Rochester fuel injection-equipped Corvette that clocked a 7.0 second 0-60 time. 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 Rambler Rebel weighed around 3400 pounds, a Chrysler 300C weighed 5000 pounds. ==Performance upgrades== ===Intake manifolds=== The 4V intake from the 250 and the 327 will bolt to the 287, which had no factory 4V option. The intake carb pattern is standard Holley [excluding the '57 models with the Carter WCFB, which has a smaller carb bolt pattern], and because the factory Holley 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 aftermarket 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,' 'air-gap' 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 be fabricated to match the angle also. The ports aren't an exact match, but can be matched within the 1/4" plate. ===Camshafts=== The camshaft can be reground to a more aggressive profile by any of the camshaft manufacturers. Call first, then send in your good used cam for regrinding. In the mid 1990s Crower, Isky and Lunati had a few virgin blanks, they have probably been used or scrapped by now, but it never hurts to ask! ===Headers/exhaust=== [http://www.andysautosport.com/headers/amc_rambler_american.html Andy's Auto Sport] has headers for some applications. [http://www.summitracing.com/parts/dou-d109-r?seid=srese1&gclid=CP2xiYG_9LgCFatj7Aod-WkAqg Doug's Headers] sells headers for the 290-401 engines, Headers By Ed has finished and plain header flanges (and gaskets for the later engines) to fit the early 1956-'65 250-287-327 AMC V8 with shared center ports as well as the later 1966-'74 290-304-343-360-390-401 AMC V8 with either rectangular or dog-leg exhaust ports along with other various header parts like collectors and tubing. On some heads the two outer exhaust ports match a 1.5" tube (easy to increase to 1 5/8") and the center two siamese exhaust ports match to a single 2" tube size. Sanderson makes a Cadillac header that could be converted by cutting the flange and slightly bending the tubes to match. Possibly 3-tube Pontiac V8 headers might be re-worked. ==Identifying AMC engines and transmissions== 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 to 1/2" from 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 Gen-1 V8 (also called 'Rambler' or 'Nash' V-8) 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). ==Identifying size== There's only one way to tell from the outside whether you have a 250, 287, or 327 cid engine. The bore is cast into the right rear top of the block just behind the head. The 250 cid block has a 3-1/2" bore, 287 3-3/4", 327 4". Other than that you have to pull the head and measure the bore. Crank and rods are the same in all three: forged steel. The cast-in number is almost impossible to see with the engine in the car, so use a mirror and try to reach back there and clean it off enough to read it. Casting numbers are way over on the side and impossible to see with the engine in the car, but here they are: *250 -- 3153077 *287 -- 3169824 *327 **1957-'62: ***3144932 ***3147230 ***3153044 ***3153055 ***3153677 ***440275 **1963-'67: ***3166463 ***4160275 There may be others for the 250 and 287, but those are the only two I have. If you find another, let me know (farna@amc-mag.com)!! ==Engine mounting== All early 250/327 engines have four-point motor mounts. Two in front of engine, two on the bellhousing. 1963-'67 327 and all 287 cid engines have side motor mounts on the block (and one near the end of the transmission) like newer cars. The early ones don't have the side mount bosses in the block, later ones have bosses for both mounting systems, but the forward most bosses may not be drilled and tapped. ==Applications== 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 327 cid engines have Carter WCFB 4V carbs, and '58-'59 327 cid engines have Holley 4150c 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 '57 4V models use a Carter WCFB 4V carb, and '58-51 4V models used the Holley 4150C carb with 8.7:1 compression and dual exhaust. The 287 appeared in mid 1963. When AMC dropped the 250 there was no V-8 except for the higher priced Ambassador. Dealers complained, and AMC made the 287 available in the Classic in mid 1963. All factory 287s came with a Holley 2V carb, no 4V option. The 4V intake from a 250 or 327 bolts right on, however, and many people have done so. ==Transmissions== ===Automatic transmissions=== AMC used GM hydramatic transmissions in 1957 switching in the '58 model year to "Flash-O-Matic" units manufactured primarily by Warner Gear Division of Borg Warner. 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. A dash mounted push-button shifter mechanism was used in the Rambler 6 and Ambassador from 1958-'62. The American models used a column shifter. The push-buttons were marked N-R-D2-D1-L, with a Park lever under the dash. P-R-N are self explanatory. In D2 the transmission will act like a two speed. It starts in second gear and shifts to third, downshifts only to second. This was mainly used for slippery conditions such as driving in snow or ice. Using second gear prevented excessive wheel spin. Many people think they have a two speed transmission because this is the third forward position on the transmission. Slip it down to D1, however, and you'll find the missing gear! In D1 the trans shifts from first through third and back down. L (low) is first gear only, no up shifts. The trans can safely be shifted into Low at any speed. As a safety feature the trans will not shift down until it has reached a safe speed to do so. If in third it will got to second, then down to first once a safe speed is reached. It will not shift back up until shifted into D1 or D2. To manually shift through the gears start in L, shift up to D1 then as soon as the trans shifts, go back to L. It won't downshift if accelerating. When ready for third gear go back to D1. 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. On the '67-'71 "Shift Command" versions, 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. These are reasonably heavy duty transmissions. They are equivalent to a Ford-O-Matic or FMX three speed, which were used behind their 352 and 390 cid engines, moreover in smaller V8 Ford 150 thru 1979. Borg-Warner's website history page states they made Ford-O-Matic in 1950. Ford contracted to buy 50% of their automatic transmissions from Borg-Warner through 1958, and built a factory to build the other 50% on their own. That's why the same trans kit will work with Borg-Warner and several Ford auto transmissions; BUT it '''is not''' a Ford transmission! The Ford transmissions '''should''' bolt to the AMC bellhousing, no one I know has tried since the older Ford transmissions and parts availability is about the same as the Borg-Warner units. 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 was discontinued. 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. When Kaiser-Jeep became part of American Motors in 1970 (AMC/Jeep) the TH400 bellhousing was switched over to the AMC V8 and 72-06 inline six pattern. AMC phased in the use of the Chrysler Torqueflite for the 1972 model year (both AMC and Jeep vehicles used the Torqueflite with the exception of the Jeep Wagoneer which continued the use of the GM-sourced THM400 until 1979 when it was replaced by the Torqueflite 727 (later the 36RH). ===Manual transmissions=== Manual transmissions used were from Borg-Warner. The 250/287 typically used a T-85 three speed and the 327 used a T-89 three speed. Overdrive was an option -- all V-8 overdrive models used the T-85 (even the 327). I'm not positive about input shaft length, but the bolt pattern is the same as other 1950s and 1960s Borg-Warner three speeds. The T-85 uses the same pattern as the T-10 four speed, and there were a few T-10s used behind the 287 and 327 in 1966. The T-85 and T-89 used different bolt patterns to the bellhousing. The T-89 is similar in appearance to the T-85 but is a heavier built transmission. ====Bellhousing bolt pattern==== The AMC Gen 1 V-8 has a unique bellhousing pattern. 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 - this includes the 258 manufactured during the 1971 model year; a majority of the small diameter bellhousing sixes had the short deck until 1970 when the 232 was casted with the taller deck but using the connecting rods from the 199. All 1972 and later AMC inline sixes (including the 1987-06 Jeep 4.0L) and V-8s use the same Gen 2/3 V8 bellhousing bolt pattern. <br><br> [[Category:Engine]] [[Category:Transmission]] [[Category:AMC]]

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