It's not your grandpa's Cadillac engine. Dick Miller's 541ci Caddy stroker uses newly developed heads plus a custom Comp Cams bumpstick and valvetrain to produce tons of tire-twisting torque at a realistic engine speed.
In these days of monster engines, the 450 ci just doesn't cut it. It seems everyone and his uncle is stroking old-school big-blocks to 500 ci and beyond. But there was one stock production engine that came standard with 500 cubes: the '70-'76 500ci Caddy. Admittedly this engine will never win Pro Stock, but with available aftermarket parts you can have a torque monster equally at home in your tow vehicle or dare-to-be-different rod. New aftermarket Bulldog heads (marketed by Maximum Torque Specialties) have the potential to really wake up GM's biggest engine.
Cores are not that hard to find. You can pick up a rebuildable 500ci Cadillac for under $500 in many areas of the country, but be careful: Externally, the Cadillac 472 appears identical--the two engines share the same block but have different-stroke cranks. The only way to tell for sure is to measure the stroke: about 41/16 inches for a 472, 45/16 for a 500.
Dick Miller Racing has long been known for its stout Oldsmobile V-8s, but when a relative needed a new engine for his Chevy pickup, Miller decided to dive into the classic Caddy using the new Bulldog heads along with PolyDyn oil-shedding, thermal-barrier, and appearance coatings; premium pistons and rods; and a stroked, offset-ground stock 500ci Caddy crank. The whole idea was to build a durable engine that maximizes performance under 5,000 rpm. As Miller points out, he ended up with an engine that makes as much torque (about 650 lb-ft) as the high-tech Duramax diesel in his $40,000 Silverado--but also churns out nearly 50 percent more power. If you like what you see, Miller can sell just the parts or build you an entire engine.
Bottom End
With their tall deck heights, Caddy blocks readily accommodate stroked cranks and long rods. Caddy lovers claim that the stock nodular-iron crank when properly prepped will live through 1,200 hp. The beefy 2.5-inch-od rod journals can easily be offset-ground down to the big-block Chevy's 2.200-inch size. That's key to parts availability, since aftermarket long-arm Caddy cranks aren't readily obtained, and it's a lot easier to find aftermarket Chevy rods and piston pins. However, two Chevy rods are wider than those in a Cadillac, so your crank grinder must also lengthen the Caddy crank's rod journals.
The 7-inch Oliver big-block Chevy rods used here are actually longer than stock 6.370-inch center-to-center Cadillac rods-yet conventional three-ring pistons fit without the oil ring impinging into the pinhole. No block-clearance grinding was needed, even with a 0.196-inch stroke increase. Another plus: The Chevy rods' small ends are bushed for common 0.990-inch big-block Chevy floating piston pins.
The 7/16-inch high-tensile ARP 2000 fasteners used in Oliver rods require a special tightening method using a Snap-on torque angle gauge.
Miller used a Total Seal ring pack. The top compression ring is Total's slant-gap design, which actually consists of two thin rings plus a support rail. The unique top-groove ring combo still needs file-fitting, but with the ring segments installed 180 degrees opposed and the rail pressure-loading them by deflecting combustion gases into the ring groove, this combo generates a nearly gapless ring with virtually zero leakdown. Marion Performance did the bore-and-hone job for the rings, which require a very specific surface finish. It also installed Miller's new billet main caps and line-bored the block.
Lubrication
The only available oil pump is a Melling stock replacement. Miller shimmed the relief spring to raise its pressure to 30 psi at idle and 60 psi at max rpm. The 0.140-inch-thick shim plus a new cotter pin for retaining the relief-spring plug is available from Miller (PN DMR-5110-C). Access to the pump is easy since it's externally mounted on a Cadillac. Other than opening up the main bearing journal oil holes to match the bearing insert holes as needed, no internal oil mods are needed to keep the Caddy alive through 5,000 rpm.
Cylinder Heads
One of Miller's reasons for doing the project in the first place was the introduction of new aluminum Bulldog Cadillac heads capable of supporting all those cubic inches. The problem was actually finding a pair, but recently Maximum Torque Specialists (MTS) acquired exclusive rights from the original supplier to produce and sell the Caddy heads. MTS has incorporated some revisions in the cores to enhance interchange with available intakes, although the material and capability remain to really port 'em for high-output engines.
In any event, Miller had Creative Flow Management's Mike Stark tune them up. "The heads needed the most help in the valve-bowl area and short-side radius," Stark says. "We did a four-angle valve job and back-cut the intake valve." On the intake side Stark cleaned up the CNC port-match and generally performed some minor deburring. Finally, PolyDyn put a thermal-barrier coating on the valve heads, combustion chambers, and exhaust runners to retain heat in the cylinder for maximum power.
Since the Caddy has only four head fasteners per cylinder, Miller seals the heads with Victor-Reinz head gaskets retained by ARP 1/2-inch studs (ARP PN 135-4007). The Teflon-coated composition-style Victor VR2000-series head gasket (PN 3852) is included in full set FS3852.
The numbers were generated on Creative Flow Management's Audie Technology flow bench at 28 inches of water. Lift is in inches. Flow numbers are in cfm.
AS-CAST PORTED LIFT INT. EXH. INT. EXH. 0.{{{100}}} 88 63 88 64 0.{{{200}}} 146 110 146 110 0.{{{300}}} 203 145 211 148 0.400 242 178 249 185 0.500 276 202 284 207 0.{{{600}}} 296 224 301 221Cam And Valvetrain
Custom-ground exclusively for Dick Miller Racing by Comp Cams, the flat-tappet hydraulic camshaft is designed to produce gobs of low-end torque with all-around driveability. It features an XFI intake lobe, an Xtreme Energy exhaust lobe, and a wide lobe-separation angle (see spec chart). Although 0.050-inch durations in the mid-230s may seem fairly hairy for a low-end torque motor, the Cad is about 190 ci larger than the quintessential small-block 350. Assuming similar cylinder-head flow characteristics, each 50ci displacement increase likes about 5-7 degrees' more duration to maintain a roughly equivalent powerband: In a 541ci engine, a cam with 230 degrees duration (at 0.050) therefore behaves much like a 205- to 210-degree cam does in a 350.
The camshaft rides on Clevite SH-30S cam bearings. Because Caddy cam journals aren't grooved the same way as Chevy's, you must precisely align the oil hole in the bearing with the hole in the journal during installation. And to prevent durability problems, be sure to coat the cam and Comp lifters (PN 869-16) with Comp's supplied lubricant and break-in additive (PN 159).
Camshaft Specs
Unless otherwise stated, all values are in crank degrees at 0.050-inch tappet lift.
Type: Hydraulic flat-tappet
Grind: Dick Miller Custom
Lobe separation (cam degrees): 113
Installed centerline int./exh.: 108/118
Duration int./exh. at 0.006 in: 274/277
Duration int./exh. at 0.050 in: 230/234
Intake opens/closes: 7 BTDC/43 ABDC
Exhaust opens/closes: 55 BBDC/-1 ATDC
Valve lift (1.7:1 rockers), int./exh.: 0.571/0.565 in
Valvespring specs
Type: Dual with damper
Manufacturer PN: Comp 950-16
Pressure (seat): 130 lb at 1.900 in
Pressure (open): 315 lb at 1.350 in
Coil-bind height: 1.200 in
Sanderson universal Caddy headers (PN CAD500) with 17/8-inch primaries and 3-inch collectors dump into Magnaflow mufflers. All dyno results are through the mufflers.
Induction, Ignition, And Exhaust
Designed for daily driveability with lots of torque, the induction system consists of an Edelbrock Performer fed by one of The Carb Shop's Stage 2 750-cfm Quadrajets. The totally refurbished carb was rebuilt with new throttle-shaft bushings and resealed throttle-well plugs. It was recolored back to the original stock appearance before being custom-calibrated for the application. A Performance Distributors ignition system lights the spark, while the exhaust is handled by Sanderson headers and Magnaflow mufflers.
Here's the engine ensconced on Southern's SuperFlow engine dyno. Except for the bright-blue paint and headers, it looks practically stock from the outside. Bosch supplied the water pump, alternator, and starter.
DYNO data
Southern Performance in Memphis is Miller's preferred test facility. Run on 93-octane pump premium with 36 degrees of advance, the engine rocked to the tune of 649.3 lb-ft of torque at 3,400 rpm, with 526.3 hp by 5,000 rpm. Grasp the total breadth of these curves: From 2,900 rpm through 4,400 rpm the engine made over 600 lb-ft. It made over 500 hp from 4,400 on up, and over 400 hp from 3,300 to 4,300 rpm.
Blueprint Data
Except as noted, all dimensions are in linear inches. For cam and valvespring specs, see the Camshaft sidebar.
Engine type: Cadillac OHV V-8
Engine builder: Dick Miller Racing
Measures And Volumes
Displacement: 541 ci
Bore x stroke: 4.375 x 4.5
Compression ratio: 10.1:1
Main journal size: 3.25 (Cadillac)
Main bearing clearance: 0.0029-0.0034
Crankshaft endplay: 0.009
Rod-journal size: 2.20 in (big-block Chevy)
Rod-bearing clearance: 0.0029-0.0030 in
Rod side clearance: 0.021-0.024 in
Rod center-to-center: 7.0
Rod/stroke ratio: 1.56:1
Piston-to-bore clearance: 0.0069-0.0073 in
Piston compression distance: 1.547 in
Crank centerline to deck: 10.794 in
Piston deck height: 0.003 in (above block)
Head gasket compressed thickness: 0.039 in
Combustion-chamber volume: 76 cc
Piston ring gap, first groove: 0.028-0.032 in
Piston ring gap, second groove: 0.025-0.028 in
Piston ring gap, oil groove: 0.022-plus in
Camshaft endplay: 0.002-0.005 in
Piston-to-valve clearance: 0.100-plus in
Critical Tightening Values
With Torco MPZ assembly lube
ARP head and main studs: 100 lb-ft
ARP rocker-arm studs: 55 lb-ft
ARP intake bolts: 35 lb-ft
With Oliver assembly lube
ARP bolts in Oliver rods: 30 lb-ft initial; rotate 40 degrees clockwise; recheck torque-should be at least 50 lb-ft
With red thread-locking compound
ARP flexplate bolts: 85 lb-ft
Grade-8 damper bolt: 85 lb-ft
Grade-8 timing-chain bolts: 35 lb-ft
Cam fuel-pump eccentric bolt: 65 lb-ft
Tune-Up
Test facility: Southern Performance
Peak power at rpm: 526.3 hp at 5,000
Peak torque at rpm: 649.3 lb-ft at 3,400
Fuel: 93-octane unleaded pump gas
Timing: 36 degrees
Spark plugs: NGK R-5671A-7, gapped at 0.055
