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AMC V8 Block Engine - Identity CrisisA Small-Block That Thinks It's A Big-Block? From the January, 2005 issue of Mopar Muscle By Marko Radielovic Photography by Ken Lazzeri
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The raw block is machined.... The raw block is machined. then the sleeves are inserted, at which point the block is put back in the machine to bore, as well as to cut clearance for the long stroke crank. AMC motors have always been stuck in an alternate universe by virtue of their physical stature. The 290 V-8 is externally the same size as the 390 and a full 100 ci smaller. Even the 401 shares the same external dimensions; so are they small-blocks or big-blocks? To confuse matters even more, Indy Cylinder Head, makers of all things Mopar, just released a new AMC block carved out of aluminum, able to support a whole lot of cubes. We followed along as Indy and Payton's Performance screwed together the ultimate bracket bomber 500-inch (yes, we said 500-inch) AMC V-8 for Mr. J.T. Payton, an AMC junkie from way back when. So what is it, a small-block or a big-block? We can tell you that with a pair of Indy's own aluminum AMC cylinder heads, this engine made big-block power at big-block rpm levels-840 horses to be exact, at only 7,200 rpm (right now you big-block guys are screaming foul, but in racing terms, this is low-rpm). If that wasn't enough, the engine weighs a light-by-small-block-standards 450 pounds completely dressed out! Chevy's own rat motor tips the scales at a portly 700 pounds. Show us a big-block that can make that claim! Indy Cylinder Head, gurus of the big-inch Mopar, and Payton's Performance, gurus of American Motors products, put together an all-new AMC V-8. So is it a big-block or a small-block? You be the judge. Just remember, whatever it is, it's 100-percent bad-to-the-bone. Who Is J.T. Payton?
J.T. Payton is an AMC nut stretching back to 1972. When he was young and on a limited budget (read: broke), he had to go the most economical route. through trial and error, he found that AMC engines were easy to keep together, as well as cheap to build. The high-nickel blocks of the 390s and 401s are tough and easy to weld if need be. Factory dog-leg cylinder heads flow better out of the box than most competitors, and if one used a closed-chamber 401 head on an earlier 343, and fly-cut the pistons for piston-to-valve clearance, they would have a low-dollar 12:1 engine. Because aftermarket parts were in limited production, the AMC rodder would have to make the factory pieces work. AMC spawned innovation. J.T. is the proprietor of Paytons Performance, the one-stop Rambler shop known as the Mecca of AMC performance circles. J.T. also races a Gremlin. So far, with only limited tuning under its belt, he's managed a very promising 8.55 at 156 mph-in a Gremlin nonetheless! J.T.'s good buddy Bill Tichenor-marketing manager at Holley Performance Products and instigator of this engine buildup-also discovered at an early age the advantages of the AMC. As a high school student wanting a musclecar and on a high school student's budget, he found the path to American Motors, as they tended to be more affordable than more mainstream musclecars. Bill found a '69 AMX for chump-change and drove it daily.  Building Blocks The time...  Building Blocks
The time is right for all you AMC fanatics out there. The aftermarket that so deftly ignored you when AMCs were actually in production, is developing some state-of-the-art parts rivaling the quality of the highest-end speed equipment available for Brand-X. Indy Cylinder Head did the unexpected when they developed this aluminum AMC cylinder block. Two versions are available: standard AMC deck height and a 9.40-inch-tall deck version for long stroke capability. The all-new IC-401 AMC Maxx block has been graced with many oiling improvements over the stock AMC offerings, billet steel splayed main caps, valley cross braces, improved head bolt clamping (an extra row of head bolts were added to use with Indy's new AMC cylinder heads), interlocking high-nickel ductile iron sleeves, all weighing in at a svelte 115 pounds. Compatible with standard AMC heads, front covers, water and oil pumps, distributors, and bellhousings make the new Indy offering as comfortable on the race track as it is on the street. Ramblers never had it so good.  The rotating assembly is the...  The rotating assembly is the foundation of any motor, and this AMC was filled with some of the best parts known to the aftermarket. A Moldex 4340 4.150-inch stroke forged crank was chosen for its obvious strength, and Wiseco 4.375-bore forged flat-tops fill all eight holes, with a 1.115-inch compression height. The Wiseco pistons utilize a lightweight .927-inch Chevy wrist pin. Any reduction in the weight of the reciprocating assembly adds to less stress and more longevity. A Speed Pro 1/16 ring pack graces the Wiseco forged slugs utilizing a .022 top gap and a .026 second ring gap. GRP 2000-series aluminum rods measuring 6.200-inches center-to-center ride on Clevite CB663HD rod bearings. The GRP rods feature radial serrations that locate the cap in all directions, ensuring perfect alignment.  The IC-401 block is fully...  The IC-401 block is fully prepped and ready for assembly. The final bore is 4.375, which is .210 bigger than a stock 401. The block weighs a miniscule 115 pounds! ARP head studs (PN 114-4203) ensure good, even clamping power across the board.  The crankshaft is held in...  The crankshaft is held in place with steel billet main caps, with splayed side studs and nuts. All main caps are doweled to the block to eliminate the possibility of cap walk.  Comp Cams was chosen to supply...  Comp Cams was chosen to supply the solid roller profile, Pacaloy valvesprings (PN 947-16) with 330 pounds of seat pressure, titanium retainers (PN 735), locks, seals (PN 506-16), and offset roller lifters (PN 892C-1) for this application. The cam features 281/292-degrees of duration at .050-inch valve lift, .748-inch lift on both the intake and exhaust side, ground on a 112-lobe separation angle (LSA). The .210 intake push rod offset helps straighten the pushrod angle.  J.T. Payton of Payton's Performance...  J.T. Payton of Payton's Performance and owner of this 500-inch aluminum AMC motor assisted with the assembly at Indy Cylinder Head. Here, he is degreeing the cam using the Milodon gear drive.  A Milodon gear drive (PN 13700)...  A Milodon gear drive (PN 13700) was used to guarantee accurate timing events. No timing chain means no stretch or potentially hazardous slippage. The balancer (PN 918640) is by ATI and is SFI certified.  Charlie's Oil Pan provided...  Charlie's Oil Pan provided this trick custom aluminum dragster-style pan with a kick-out and starter pocket that uses an Indy #340 swinging pickup. The oil capacity is eight quarts. The Indy/Razor billet single-stage oil pump has an external pressure adjustment.  Indy builds their own AMC...  Indy builds their own AMC timing covers, as well. This one is shown with an MSD billet distributor and billet oil pump. This cover will also fit a stock cast-iron AMC block and works with the stock-style internal pickup and standard mechanical fuel pump.  The single-stage oil pump...  The single-stage oil pump takes oil from the pan (via a -12 AN line) and pumps it out to a remote filter. From the filter, the oil goes back into the block. Since the cam drives the distributor, and the distributor in turn drives the oil pump, an MSD small-block Chevy crank trigger kit was modified to fit the Indy AMC timing cover. Crank triggers ensure steady timing events.  Indy's CNC-ported heads get...  Indy's CNC-ported heads get five-axis porting. The process takes four hours per head, but the end result is every port has uniform shape and size.  Indy's new 401-1 CNC cylinder...  Indy's new 401-1 CNC cylinder heads are a work of art, featuring 300cc intake runners, that reportedly flow 390/282-cfm on the intake and exhaust respectively! Stock AMC "dog-leg" heads have roughly 166cc intake ports. With a 58cc combustion chamber, a flat-top piston will get you up over 14:1 compression. Indy o-ringed the heads, and fitted them with Manley 2.25/1.81 intake/exhaust valves. Indy built their heads so that they have six bolts per cylinder. The 401-1 is essentially a big-block cylinder head for a small-block, and at 300 cc, nearly perfect for a bracket racing engine in the 470 to 500ci range.  The outboard 7/16 head stud...  The outboard 7/16 head stud bosses are for use with the IC-401 Maxx block that has been equipped with six bolts per cylinder. On the exhaust side, Indy used a Chrysler 440 pattern to space and help cool the center exhaust ports.  Jesel's state-of-the-art shaft-mounted...  Jesel's state-of-the-art shaft-mounted roller rockers (PN KCS-22044) were used in a 1.7:1 ratio. The trick sheetmetal valve covers are made by Indy (PN 401-8).  The Jesel mounting bar uses...  The Jesel mounting bar uses eleven 7/16-inch mounting bolts. Combined with Indy's own 3/8-inch diameter pushrods (PN 401-9) and Comp's offset roller lifters, the end result is one bulletproof valvetrain. Here, J.T. is lashing the valves on his monster Rambler motor.  The ignition system on the...  The ignition system on the 500-inch AMC is all MSD, featuring a Pro Billet distributor (PN 8519), crank trigger (PN 8600), and plug wires (PN 31189). Indy made the custom crank trigger bracket that adapts the small-block Chevy crank trigger to the AMC timing cover.  Making over 800 hp requires...  Making over 800 hp requires a pretty serious induction. Indy stepped up with this new 401-2 high-rise, single-plane, single-quad intake manifold, using a 440-2A Dominator adapter. The intake is fully ported and polished for maximum performance. The Holley 1150 Dominator is from their new Ultra-series featuring billet metering blocks, and a big site glass to set the float level with accuracy.  So there you have it. Is it...  So there you have it. Is it a 290? 343? Nope, 500 inches of aluminum small-block knocking out a reliable 840 hp and a very un-small-block-like 675 lb-ft of torque. The headers were made from a Hooker weld-up kit (PN 2957HKR) for a big-block Chevy. Indy supplied the flanges and the primary tube size is 2 1/4 inch.
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