|
|
Part 2: Building the Slant SixSix Equals Eight From the April, 2003 issue of Mopar Muscle By Steve Magnante Photography by Steve Magnante
|
|
 Gene Ohly at Evans Speed Equipment...  Gene Ohly at Evans Speed Equipment prepared the rare alloy block forassembly. The integrally-cast iron liners had some scratches, so theywere bored 0.020 oversize. The liners are a mere 0.10 thick, so the lessmetal removed, the better. Iron blocks can safely be bored in excess of0.060. Ohly also align-honed the mains, burnished the lifter bores, andsquared the deck surface. The fully machined block weighs 64 pounds, 70pounds less than iron.  Addressing the different rate...  Addressing the different rate of thermal expansion between aluminum andsteel, Chrysler employed unique upper and lower main-bearing caps. Theupper caps (installed in the block) are specific to aluminumapplications and feature roll sleeves to assure proper positioning. Thesleeves are used on the driver side of the block only and must never beinstalled on the passenger side. A critical oil passage intersects thepassengerside main cap bolt hole to feed oil to the main bearings. Afteralign-boring, iron-block lower caps can be used with aluminum blocks.  Although the aluminum block...  Although the aluminum block has no cam bearings, any Slant Six cam fits.Thanks to the continuous oil bath present in the area during operation,lubrication is assured, even when high-pressure valve springs are used.  The main-bearing oil-feed...  The main-bearing oil-feed holes differ in iron and aluminum blocks.Here, a pen points to the lower hole used in iron applications.Fortunately, virtually all Slant Six main-bearing sets sold today arealso drilled with the higher hole required by the aluminum block. Thegrooved upper shells and nongrooved lower shells of our Enginetechbearings are adequate for our 5500-rpm ceiling. Main-bearing clearanceis 0.002.  To help prevent leaks, Doug...  To help prevent leaks, Doug offsets the rear main seal in such a waythat the gap is not aligned with the cap and block parting line. Theneoprene seal has a lip that acts as a one-way, valve-to-oil passage.The lip must face inboard, toward the crankshaft, for proper function.  The crank is from a '72 donor...  The crank is from a '72 donor engine with minor polishing. Though allSlant Six cranks produced between 1960 and 1976 are beefy forgings,those from 1968 and later feature a 2.160 diameter flywheel/flexplateregister that accepts commonly available torque converters andflywheels. The pre-'68 register is smaller (1.960 diameter) and must usehard-to-find corresponding transmission components. All forged cranksare neutrally balanced, so mixing production parts rarely causesproblems. Cranks manufactured in 1977 and later are made of cast-nodulariron and have narrow main and rod bearings. Cylinder blocks, cranks,rods, and bearings from 1977 and later engines will not interchange withearlier Slant Sixes.  The main bearing bolts are...  The main bearing bolts are tightened to 50 lb-ft (versus 85 lb-ft foriron blocks) to suit the physical properties of the die-cast aluminumblock. Antiseize compound is applied to prevent thread and shouldergalling. Chrysler testing revealed that if the thread engagement of thecap bolt into the aluminum is 21/2 times as long as the thread diameter,the bolt shank fails before the host aluminum. The special 1/2x13 capbolts are an inch longer than those used on iron blocks and featurereduced shanks to provide aluminum-compatible stretch characteristicsand to allow the passage of oil through the bulkheads to the mainbearings. Crankshaft endplay is 0.045, the same as an iron block.  Basic, rugged, and cheap,...  Basic, rugged, and cheap, stock 6.7-inch forged rods with ARP 3/8-inchfasteners and cast-aluminum Enginetech 0.020 oversize pistons can handleplenty of abuse. The slugs weigh 16.4 ounces, and ours came sized within0.00025 diameter and 2 grams of each other. The Sealed Power chrome-molyrings ensure fast break-in and have 0.014 endgaps. The rods weigh 26.8ounces and should be installed with the oil squirt holes facing thepassenger side. The D-shape heads of the ARP rod bolts require a minorspot-facing operation on the rod shoulder for proper installation.Rebalancing of these stock-replacement parts is a luxury we skippedwithout consequence. Rod-bearing clearance is 0.001. In a previous issue, we told the story of the aluminum block Slant Six and how its brief production run (1961-'62) was cut short by manufacturing difficulties and unexpected costs. This month we team up with Slant Six engine guru Doug Dutra to show you how to build a Slant Six that'll make 1hp/cubic inch, live with 91 octane unleaded, and run low 14s at over 90 mph in a 3,000-pound A-Body while remaining totally streetable and delivering 15 mpg. Our buildup is based on a cherry aluminum block that somehow managed to escape the terminal, from-the-inside-out corrosion that renders most surviving blocks useless. Though our alloy wonder weighs 70 pounds less than much more common cast-iron blocks, if you follow our recipe with your iron block, you'll get identical results. Note for the following: (a) Included in price of '72 donor motor; (b) Optional Recipe List
Displacement: 227 ciCompression ratio: 9.2:1Bore/stroke: 3.420 by 4.12 (0.020 overbore)Bore/stroke ratio: 0.830:1Rod/stroke ratio: 1.63:1Recommended shift points: 5,000 rpmRequired fuel: 91 octane, unleadedDeluxe price: the aluminum motor shown here cost us $4,252.93El Cheapo price: an iron motor without optional frills (b) would cost approximately $3,351.51Short-Block (Deluxe: $709.17; El Cheapo: $459.17)
Block: 1962, die-cast aluminum, bored 0.020 oversize, $250 (b)Machine work: $200Crank: '72 forged steel (a)Balancer: stock Chrysler (a)Rods: stock Chrysler, forged steel, 6.7-inch (a)Rod Bolts: ARP 3/8-inch, PN 142-6001, $76Rod bearings: Clevite 77, PN CB-606G-STD, $32.42Main bearings: Enginetech PN BC312J-STD, $39.46Pistons: cast-aluminum Enginetech 0.020 oversize, PN P1515-020B, $59.92 (b)Piston pins: Enginetech press fit (with pistons)Rings: Sealed Power chrome-moly, PN E-196K-20, $51.37Main cap fasteners: original aluminum block Chrysler 1/2x13 boltsOiling System, $14.00
Oil pan: stock '62 ValiantOil pickup: stock (a)Oil pump: cleaned up stock (a)Oil: 5 quarts 10W30, $10Oil filter: Fram PH8A, $4Cylinder Head (Deluxe: $1,363.67; El Cheapo: $1,236.20)
Type: cast iron (a)Modifications: deck milled 0.100, oversize hardened seat inserts, bronze valve guides, valve guide bosses milled 0.160, six hours worth of bowl blending, and port-relief work, $600Valvesprings: Pioneer single with damper, PNS-1051, $75Intake valves: Egge Machine stainless, 1.70-inch PN SPV857, $162Exhaust valves: Egge Machine stainless, 1.44-inch PN SPV856, $150Retainers: Engle chrome-moly, PN599-S, $62.25Locks: stock Chrysler, two-groove (I), four-groove (E) (a)Valve seals: Pioneer neoprene umbrella-type, $6.95Rocker arms: stock Chrysler, stamped steel 1.50:1 ratio (a)Adjusters: stock Chrysler (a)Pushrods: stock Chrysler 5/16-inch (a)Valve cover: Clifford cast-aluminum PN 45-4018, $109.97 (b)Valve cover bolts: MP chrome, PN P4120272, $12.50 (b)Head stud kit: custom ARP 7/16 heat-treated studs, $115Head gasket: N.O.S. McCord PN6530M, $75Camshaft, $360
Type: Engle PN KV-1, $220Running duration: 271/271Duration at 0.050: 240/240Lift: 0.546/0.546Lobe center: 108 degreesLash setting: 0.010 (I), 0.020 (E)Lifters: Engle solid PN862, $105Timing chain: Enginetech silent-type single row with steel gears PN TS495, $35Ignition (Deluxe: $395.73; El Cheapo: $199.78)
Distributor: MP electronic conversion kit, PN P3690789, $139.88Control module: MSD 6AL PN 6420, $195.95 (b)Coil: MSD Blaster II PN 8202, $28.95Wires: Accel Super Stock 8mm universal fit, $23.95Spark plugs: Autolite 66, gapped at 0.035, $7Timing specs: 30-degree BTDC total, all in by 1,500 rpmVacuum advance: noneMisc (Deluxe: $788.41; El Cheapo: $460.41)
Running '72 225 donor engine: $100Water pump: Pep Boys, $29.99Air cleaner: Mopar Performance chrome resto, PN P4529002, $120Fan: stock Chrysler five-blade (a)Fan belt: Gates, $9.50Water-pump pulley: stock Slant Six (a)Starter: stock Chrysler (a)Alternator: stock Chrysler (a)Fuel pump: Airtex mechanical, $39.95Rear main seal: FelPro PN BS40240, $12.99Timing cover set: FelPro PN TCS12769-1, $17.99Oil-pan gasket: FelPro PN OS12705 C-1, $12.99Headers: Clifford two-piece street rod headers, PN 55-0144, $237Header coating: Jet Hot sterling, $195 (b)Paint: Two cans of MP engine red, PN P4349218, $13 (b) At TDC, the piston is 0.180...  At TDC, the piston is 0.180 below the deck. And despite our 0.546-inchlift cam and heavily-milled head (0.100), the clay test revealsvalve-to-piston clearance of 0.310 intake and 0.270 exhaust. That'sthree times the safe minimum.  Mopar Muscle tech meister...  Mopar Muscle tech meister Steve Dulcich talked us into using the EngleKV-1 solid cam and lifter set. We're glad we listened. Despite its wildspecs (see Recipe List), it has good street manners and is a perfectcomplement to the test car's 3,000-pound race weight, 3.55 axle ratio,9.2:1 compression ratio, and 2,700-rpm stall speed. We installed it 2degrees advanced after drilling the cam-gear dowel hole from 0.250 to0.270 and installing a 0.020 shim (flattened coat hanger) to re-indexthe gear on the cam snout. The single-roller timing chain and steelgearset is cheap but effective. Double roller alternatives are availablebut offer no benefit at this level of performance. By all means, avoidplastic-coated cam gears, as they tend to shed teeth with severe use.  The stock head needs help...  The stock head needs help for performance use. Gregg Hansen of Stage VEngineering spent an afternoon relieving the bowl areas, enlarging theports, and gasket matching. Then, Gene Ohly milled 0.100 off the deck,reducing chamber volume from 54 cc to 44 cc, bumping compression to9.2:1 with the stock-replacement flat-top pistons. He also installedoversize hardened seats and bronze valve guides and performed athree-angle valve job. If you're building an aluminum block, tell yourhead porter not to back-cut the chamber walls adjacent to the valveheads to unshroud them. Doing so reduces the area available to pinch thehead gasket's fire ring and can lead to chronic gasket failure. Our headwas unshrouded slightly (note the 8 and 2 o'clock positions), but we gotaway with it.  The height of the valve guide...  The height of the valve guide bosses must be reduced for safe retainerand seal clearance at full lift. Oscar Alvarez at JMS Racing Engines cutours from .750 to .590 and also machined the outer diameter of thebosses to clear the valve spring's flat-wound inner surge dampers (seepointer).  The stock 1.62/1.36 valves...  The stock 1.62/1.36 valves are replaced with 1.70/1.44 stainless valvesfrom Egge Machine. The Pioneer S-1051 single with damper valve springshas an installed height of 1.750 intake and exhaust where it exerts 120pounds on the seat and 260 pounds at the cam's .546 maximum lift. Bycomparison, stock Slant Six springs rate 144 pounds at full lift(.371/.364 stock cam). Engle chrome-moly retainers replace the stampedsteel stockers, while stock Chrysler locks are reused. Neopreneumbrella-type valve seals control oil.  Like the main bearing caps,...  Like the main bearing caps, the soft aluminum block requires specialhead fasteners. The original reduced shank 7/16x14 bolts were lost, soAl Nichols and Mike Rose of ARP tooled up a new head-stud kit just forus and any other aluminum-block customers who might need a set. Theseheat-treated 7/16 studs can be threaded deeper into the block than boltsfor increased thread engagement, and they offer superior clamping force.Using antiseize compound, they torque to 60 lb-ft (iron blocks go to 75lb-ft). Aluminum blocks take a special head gasket that's only availableas N.O.S. and must be retorqued after initial startup. Remember toinstall the lifters before the head on all iron blocks. The open deck ofaluminum blocks allows for later lifter installation...  The rearmost rocker-shaft...  The rearmost rocker-shaft pedestal on all Slant Sixes is counter-bored(see pointer) to feed critical oil to the rocker shaft and rocker arms.It requires a specific 3-inch long hold-down bolt (on right). The otherfive hold-down bolts are 2 inches in length. Torque them all to 30lb-ft.  There is a lot of confusion...  There is a lot of confusion regarding proper rocker-shaft orientation.Here, the pen points to one of the 12 oil-squirt holes that lubricatethe valve stems and rocker arms. They must be targeted at the driverside of the engine or valve-tip/rocker-pad failure will result.  They may not look sexy, but...  They may not look sexy, but the stock 1.5:1 stamped-steel rocker armsare an engineering marvel and are fully capable of living with our hotcam and stiffer springs. The same goes for the stock 9.984-inch long,5/16-diameter pushrods. Despite the hefty head milling, the stockadjusters can take up the slack without introducing geometry problems.If both the block (iron only) and head are milled, shorter custompushrods would likely be required. We set the valve lash at .010(I)/.020 (E) cold with iron or aluminum blocks and check it every monthor so.  Unless you're going to the...  Unless you're going to the moon, the stock oil pump works great. Justchamfer the oil-filter return passage and any other accessible junctionsto remove sharp edges and promote oil flow. High-volume pumps tend tooverload the small drive gear, leading to total oil-pressure loss. We'vebeen there and it's not pretty. Now we only use blueprinted stock pumpsin sub-5,500 rpm applications like this. For extra peace of mind, Dutraoffers a special heat-treated pump drive gear at www.slantsix.org.  Since we milled the head,...  Since we milled the head, we slid a .040-thick flat washer between thealternator bracket and head to prevent strain and possible bracketcracking.  Clifford two-piece headers...  Clifford two-piece headers fit our '62 Valiant test car without hassles.They feature 11/2-inch primary tubes, 21/2-inch collector outlets, andcorrect 1/2-inch flanges for compatibility with factory or aftermarketintake manifolds. Some other headers use thinner flanges that requirefussy shims to prevent gasket leaks. Jet Hot sterling coating keeps themlooking new inside and out.  A sight to warm the heart...  A sight to warm the heart of any Mopar fan, the once scarce Slant SixHyper-Pak intakes are back in production thanks to a collaborationbetween Doug Dutra and Clifford Performance. Here, Larry Clifforddisplays some fresh castings.  The outrageous appearance...  The outrageous appearance of the cast-aluminum Hyper-Pak intake is whatoriginally rekindled our interest in the Slant Six. Pop the hood at acar show and even die-hard Chevy guys flip out. Though original '60Hyper-Pak kits included manifold support bracing, we just bolt 'em tothe head's numerous 5/16 studs and go. The whole unit weighs 30 poundswith the carburetor.  Instead of the scarce and...  Instead of the scarce and troublesome rod and bellcrank Hyper-Pakaccelerator linkage, take a 2.2 K-car throttle-cable bracket (stamped426880), shorten it, and weld on a tab as shown. This bolts to the backof the plenum and accepts a throttle cable pirated from any Chryslerminivan.  The 500 cfm Edelbrock Performer...  The 500 cfm Edelbrock Performer carburetor works perfectly right out ofthe box on our displacement- challenged six-banger. Aside from a nearlyimperceptible dip when floored from 60 mph, it doesn't stumble orhesitate, even though it's nearly 2 feet from the engine. True to theSlant motor's legacy of efficiency, we're seeing regular 15.1-mpg fueleconomy numbers when we keep our foot out of it. For simplicity, weremoved the choke blade and still get easy start-up on 45-degree wintermornings in California. Just tickle the throttle to keep it lit, andwithin a mile it's running smooth. We hear Hyper-Paks suffer from thecarb icing in cold, humid weather, but we haven't noticed it yet.  We dig the Hemi-like aluminum...  We dig the Hemi-like aluminum spark-plug tubes and rubber booties usedon pre-'75 Slant Sixes, but we want a better ignition cable than stock.So we slipped an abbreviated section of insulator over our 8-mm AccelSuper Stock wires. Then we worked the circular tube seals over theinsulators.  Doug Dutra is one of the leaders...  Doug Dutra is one of the leaders in the Slant Six performance-development field. We thank him for his help with this story. You canlog onto www.slantsix.org to chat with Doug and other Slant Six owners.
|
|
|