Performance Information
1965 AMC Rambler Marlin
Performance Information
For Gearheads and Thinkers
Cutaway View of V8 Engines
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For many years now I have seen other engines swapped into AMC cars. My only explanation for this is a lack of good information. Other enthusiasts consider AMC cars to "muts"; not thoroughbreds, but GM and Ford used Borg Warner transmissions also. (I don't know the details, but apparently Ford purchased the rights to manufacture the BW M8-12 auto tranny around '67, and making changes to the design they named it "FMX". Not absolutely sure, but I think this is why AMC went to Chrysler automatics in '72; not to surrender to Ford's manufacturing tyranny. Keep in mind, it can be proved sub-entities of Ford (not actually FMC, but underling cronies) did fabricate disinformation to put the smaller makes out of business. But I like Ford products; the '71 429 Ram Air Mustang Mach 1 is my favorite Ford) It slapps me silly to see a Chevrolet engine in an AMX; a car that smashed over one hundred speed records with it's very own AMC V8. The Metropolitan also; it's Austin Motor Co. (AMC!) engine is truly a legend. Raced for decades in MG's and Austin Minis, tons of high performance parts are available for it, but Mets get butchered anyway. How about putting a Ford Windsor engine into a Chevy Nova; joke right? Only for ignorance AMC cars are made into Frankensteins. These are historical cars with historical engines that should be respected as such, but AMC cars are not, for lack of good information. I aim to dispel this confusion about AMC products in general.
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Rambler 327 V8 pistons have about 1/2" more piston pin height than Chevrolet small block 327, but same bore size. Piston temperatures vary greatly from the piston dome/face down to the tips of the "skirts". For this reason, the "extra" piston pin height found in the Rambler V8 is to reduce the temperature of the piston pin for longevity. However, the reduced piston pin height found in Chevrolet's 327 has not proved to be a durability issue. Most crank shops can build up the rod journals 1/4" with welds to achieve the additional 1/2' stroke in a Rambler V8. (Crank journal welding is normally done when an engine "spins a bearing", to resurface the rod journal.) See also http://wps.com/AMC/Rambler-327/418-cid%20v8.htm
Genuine thanks to these Rambler enthusiasts for posting all this good information. However I would not recommend the Rambler V8 for turbocharging because I have not yet found suitable high performance head bolts, and I dissagree that the Rambler V8 is a good engine for turbocharging because it is a "thick wall" casting; it is not. Rather the "extra" weight compared to the AMC V8 is easy seen in the "deep skirt" crankshaft gallery "X" bracing, the cast iron timing chain cover and water outlet manifold, and various aspects of the the rear of the engine block -the bolt pattern bracing and general extension. As explained in the technical article, the extra bracing is for cancelling slight vibrations in the engine especially at certain points in the power band, but also for a long lasting union to the transmission's input assembly. Both Chrysler's famous Hemi V8 and Ford's legendary FE V8 engine had main bearing flex problems that had to be solved after the initial design and tooling processes.
This gasket manufacturer seems like they are true Rambler V8 enthusiasts judging by their careful and complete quality gasket sets. -More power to 'em!
Regrind service. AMC supplied all Rambler V8s with same cam specs. While the 250 cid version used solid lifters having adjustable rockers, the cam's lobe design was carefully engineered for longevity, making sure the valvetrain components operate very smoothly with no excessive scrubbing. Unlike the highly touted Chevy small block V8 that was made with square shouldered (non rotating) valve spring retainers and a bonnet over the valve spring for oil control, AMC employed positive rotating valves using umbrella type valve stem seals. Rambler V8 valves and lifters are the same size and type as the later model AMC 304 V8, so it's logical to expect a high performance/rpm valve spring kit and performance type anti pump lifters are already available at any hi po part dealer. For the performance enthusiast, the cam should be optimized for bore and stroke changes. The camshaft regrind service business of the enthusiast's choice should be able to overcome any falsely perceived valvetrain mystery and should require an exhaustive list of scientifically pertinent specifications in order to supply the type of reground performance cam the client desires. Don't just take my word on this subject; there is good information out there about the technical aspects of camshaft and valvetrain science for anyone to study and make their own decisions. One thing for sure is the Rambler V8 is a good base to build power into, easier than say a Buick "Nailhead" V8; to overcome the restrictive ports and unusually small valves (hence the nickname hinting at the small valve sizes) racers used to have those cams done transposed in order to reverse flow the heads, supercharging the exhaust ports and using the intake ports for the exhaust outlets!
Taken off the car, the Marlin's automatic transmissions are among the easiest to rebuild. The labor involved to swing away torque tube drive system is more difficult than an open driveshaft car. Please contact me about any pre '72 AMC Borg Warner automatic transmission problems. I can do your old BW trans service confidently, for performance, and you can save about $1500! -no lie- The big shops must have a lot of overhead, but I'm probably not alone in cringing to tell my transmission shop disaster experiences.
So you think old Ramblers are boring? Take that fat wallet full of credit cards here! The AMC V8 is a near bolt in swap for the Rambler V8. Any '67-'72 AMC V8 automatic bellhousing is your adapter. For $12,000 + price of Grandma's Rambler Classic, one could have a real hot rod by golly.
"Headers By Ed " makes header parts for the Rambler V8; everything from premade flanges to three into one collectors. Advice how to do Rambler V8 headers. Moreover, since the Rambler V8 employs a free standing intake manifold above it's covered lifter valley (surprise under valley cover is baffle to direct fresh oil poured in, and separate "block hugger" lifter valley cover to direct bulk of top oil to drain down in rear of block above rear main and oil pump. Aside from intake manifold temperature control the seperation maintains that no oil is scalded from splattering upon the cross over exhaust heat riser, thus extending the life span of the engine oil)... easier than doing the headers, would be to make a steel tube intake (again, racers in the sixties used to do that) From my studies, I calculate that 1 1/2" x 13" tubes for each intake port would result to 17 to 18" intake runners (4 1/2 long ports in head). This should be about optimal for mid range torque. (having the steel tube intake -or valve covers- chromed will look great, but under the hood black paint releases heat better -one reason why eventually AMC went to black engine paint. In raw sunlight, white, silver or chrome is better to reflect/keep heat out) Apparently the runner extensions should tie into a common plenum about 1 1/2 the size of one cylinder's displacement. One of my dreams is to make a steel tube tunnel ram like this. I would make the common plenum about one cylinder's displacement and to have a bolt on cover plate to add spacers for more volume and to have options for a variety of carburetor selections... -the dream is to fabricate a three twos ("six pack") intake and a seven tube header, to make a Rambler 3-2-7 (the Rambler V8's have siamese center exhaust ports, for three tubes on each side -then a cross over tube near the collectors makes seven tubes) Anyway, don't assume that since there is no bolt on aftermarket aluminum intake or ready made exhaust headers that this engine has no potential! As far as the Rambler V8 goes, you are only limited by your own potential to think and do for yourself. If one has no training to work with metals, ask around to find a good metal fab shop; they'd probably enjoy doing the job for the sake of interesting variety.