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1965 Oldsmobile Cutlass Project Car - The OldsmobeastWe Bid Farewell To Project Olds' 330ci Small-Block, And Build A Torquey 514hp Big-Block To Take Its Place. From the June, 2010 issue of Popular Hot Rodding By Stephen Kim Photography by Stephen Kim
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For the typical street/strip motor, hot rodders have been aspiring to match towering horsepower peaks with excellent low and midrange torque for decades. Get that curve flat enough, and you've got yourself a broad and flexible torque plateau opposed to a narrow and finicky peak, which aptly describes the performance of the 461ci big-block Olds we recently built for our '65 Cutlass project car. While its 514 hp is more respectable than delectable, the Olds' maximum torque output of 540 lb-ft-which extends from 4,100 to 4,600 rpm-is both remarkably stout and astoundingly flat. Furthermore, the big-block Olds kicks out 494 lb-ft at just 3,000 rpm, and averages over 500 lb-ft throughout its entire operating range of 3,000 to 6,000 rpm. Sure, it's not terribly difficult to eclipse 500 hp with a run-of-the-mill small-block Chevy in the current era of easy horsepower, but it's the gobs of twisty stuff-and how cheap and easy it is to attain-that sets this 461 Olds apart from the pack. Searching for a core locally... Searching for a core locally proved fruitless, so we tracked down a nice 455 on eBay for $500. The motor was pulled from a '71 442 and displayed minimal wear upon teardown. The seller kindly stripped it down to the bare short-block before shipping it out. While all these numbers look great on paper, they work even better in practice. The Tremec TKO-600 five-speed trans, 3.73:1 ring-and-pinion set, and 26.7-inch tires the 461 will be paired with match its torque curve perfectly. Assuming a shift point of 6,000 rpm, the big Olds will never fall more than 100 rpm outside of its broad torque peak on the 1-2, 2-3, and 3-4 shifts. Not only does that bode well for our '65 Cutlass' autocrossing endeavors, all that torque makes for an extremely well-mannered street combination that packs a devastating wallop from right off idle all the way to redline. Using a stock crank, a .030-inch cleanup bore, Edelbrock aluminum heads, a Mondello single-plane intake manifold, and a COMP hydraulic flat-tappet cam, the combo is as simple as it gets. To transform our stack of parts into a thumpin' big-block, we hit up the expert engine builders at the School of Automotive Machinists in Houston, Texas. Although many readers recognize SAM for its perennial success at the AMSOIL Engine Master's Challenge, its primary objective is teaching students how to build performance street and race motors. Under the tutelage of school director, Judson Massingill, and head instructor, Chris Bennett, SAM's students carefully machined, balanced, assembled, and dyno tuned our 461 Olds from start to finish. The graduates the program churns out are hot commodities amongst the upper echelon of racing, and in fact, the student who ported the cylinder heads for our big-block Olds is now working for Warren Johnson's Pro Stock team. Considering that the Olds 455 and the Olds brand have both kicked the bucket, the young 'uns were psyched by the opportunity to work on an engine platform that precedes their time. Piston and rod selection for... Piston and rod selection for Olds motors is somewhat limited, but the parts that are available are very high quality. The stock-length 6.735-inch Eagle steel rods used in our 461 are good for 850 hp, and they were paired with 4.155-inch SRP forged pistons. Thanks to the Olds' tall 10.625-inch deck height, the pistons have a meaty 1.750-inch of compression height.
Back in the glory days of intra-GM rivalry, Buick, Oldsmobile, and Pontiac built a triumvirate of 455s. Unlike their high-winding 454ci Chevy counterpart, the BOP boys settled upon their own unique combinations that emphasized torque over horsepower, and this focus on low and midrange grunt is clearly evident in their engines' basic architecture. With a 4.125-inch bore and a 4.250-inch stroke, the 455 Olds' under-square dimensions loudly telegraph its stump-pulling intentions. Granted, the 4.250-inch stroke-one of the longest ever used in any muscle car engine-doesn't increase torque output much at all, it does shift the torque peak lower down in the rpm range and broadens the area under the curve. In comparison, the over-square 4.250x4.000-inch Chevy 454 is more inclined to turn greater rpm and make its power higher up in the rev band. The combination of a long stroke, lots of cubic inches, and modestly sized cylinder head ports set the stage for making gobs of torque in a hurry. Torque monsters, by nature, don't need to turn high rpm, so the Olds 455 features beefy 3.000-inch main and 2.500-inch rod journals to increase journal overlap and enhance crankshaft strength. While larger journals increase bearing speed and friction, its adverse effects are fairly insignificant in a low-rpm motor like the 455. Since big horsepower at high rpm was never a likely scenario with a 455, the block casting is quite a bit lighter than a Chevy 454 as well. Rumored weight differences between the two vary greatly, but conservative guesstimates claim that the Olds weighs in at 50-75 pounds less than a comparable big-block Chevy.  SRP offers off-the-shelf big-block...  SRP offers off-the-shelf big-block Oldsmobile pistons for both .030- and .060-over applications with -5cc valve reliefs. The 4032 forgings have a silicon content of roughly 12 percent, which tends to be more brittle at high temperatures than a 2618 alloy piston. The advantage of a 4032 alloy piston is that it expands 15 percent less, which allows running tighter piston-to-bore clearance for reduced blowby and piston slap.  Since the 461 Olds is more...  Since the 461 Olds is more street than race, we matched the pistons up with a set of 1/16-, 1/16-, 3/16-inch JE standard tension rings. SAM set the top ring gap at .026 inch, and the second ring at .028 inch. In stock trim, Olds motors... In stock trim, Olds motors have weak oil return systems that flood the cylinder heads at high rpm. The result is too much oil in the top, and not enough in the pan. To help keep the oil in the pan, Mondello set us up with its oil restrictors, which were tapped into the oil galleys in the main bearing saddles. Likewise, the oil holes in the main bearings were enlarged, and cam bearings with smaller oil holes were installed as well.
One universal tenant of any successful engine build is capitalizing upon the strengths of your engine platform of choice, and playing down its weaknesses. In the case of a 455 Olds, that entails keeping the operating range reasonable, and maximizing low and midrange performance rather than having delusions of high-rpm glory. Moreover, not-so-common engine platforms like the 455 can run up a big bill, as aftermarket parts are far less plentiful than with a Ford or a Chevy. Consequently, the goal with our 461 was to keep the build as simple as possible while shooting for 500 hp and 525 lb-ft, and limiting engine speed to 6,000 rpm. As it turns out, we exceeded our power and torque targets ever so slightly while capping the total for parts and labor at $8,500. Given our power and torque objectives, there wasn't much need to expand displacement much beyond 455 ci. Starting with a stock 455 short-block pulled out of a '71 442, we discarded the factory rods and pistons and increased the bore 0.030 over to 4.155 inches. Although some Olds blocks can be bored 0.120 over, doing so can compromise cylinder wall strength and requires custom pistons in most instances. On the other hand, 455 blocks have sufficient wall thickness for up to a .060 overbore without the need for sonic checking, and off-the-shelf pistons are readily available in 4.155- and 4.185-inch diameters. We opted for a set of SRP 10.44:1 forged pistons, and matched them up to stock-length Eagle 6.735-inch steel rods.  Mondello's high-volume oil...  Mondello's high-volume oil pump uses 7/8-inch internal passages for a significant improvement in flow and volume over a stock pump. To further improve oil flow, SAM students enlarged and radiused the oil passage on the number five main cap before bolting down the oil pump.  The crank in our core 455...  The crank in our core 455 was in excellent shape, but SAM decided to play it safe by turning the journals down .010/.010. The lightweight aftermarket pistons and rods required removing 180 grams out of the counterweights to achieve proper balance. For a more pleasing look, instead of drilling holes into the counterweights, they were turned down in a lathe.  As luck would have it, our...  As luck would have it, our core motor was equipped with a nodular iron crank, denoted by the "N" cast into the front counterweight. Thanks to the stock-length stroke, the short-block went together without any drama. Only the bottom of the rods had to be massaged, as they were contacting the bottom of the cylinders just slightly. Parts and labor for a four-bolt... Parts and labor for a four-bolt main cap conversion would have rung up another $1,000, so SAM stuck with the factory caps and anchored them in place with ARP studs. The main and rod bolts were torqued down to 100 and 60 lb-ft, respectively. So far so good, but the selection of aftermarket Oldsmobile crankshafts is miserably limited. While aftermarket forgings are available, most are only offered with the stock 4.250-inch stroke. Fortunately, with big 3.000-inch main and 2.500-inch rod journals, factory 455 cranks are plenty stout. A very small number of 455s were blessed with forged cranks from the factory, but they're nearly impossible to find these days. Most came equipped with cast- or nodular-iron crankshafts, which, thanks to their generous journal overlap, can easily handle up to 650 hp. Considering the durability of the stock nodular crank in our 455 core motor, it made no sense to shell out big dollars for an aftermarket forging. Instead, we simply turned the journals .010/.010 and called it a day. If you're building a heavy-breathing Olds that has enough cylinder head airflow to take advantage of some extra cubes, it is possible to offset grind a factory 4.250-inch crank to 4.500 inches. This simply involves grinding down the Olds' big 2.500-inch crank pins to 2.200 inches, and hooking them up to big-block Chevy connecting rods. If that's too much of a hassle, Eagle has just released a 4.500-inch cast steel crank with big-block Chevy crank pins that lists for under $600. Combined with a 4.155-inch bore, a 4.500-inch crank would yield a total of 488 ci. Although an extra 27 ci over our 461 is certainly enticing, the custom pistons and the extra machine work it would require make it a very expensive proposition.  Tightening up the quench area...  Tightening up the quench area improves power output and resistance to detonation. SAM students set the deck height at -.005 inches, which still leaves enough metal on the block deck for future rebuilds.  Excessive endplay can chew...  Excessive endplay can chew up the crankshaft's thrust surfaces. SAM students dialed it in at .006 inch.  Proper connecting rod side...  Proper connecting rod side clearance helps center the rods on the wrist pin when using floating pins. It also ensures adequate oil flow through the rod bearings to keep them cool. On our Olds, the rod side clearance was set at .018 inch. One of the most common mistakes... One of the most common mistakes when assembling a motor is bolting up the oil pan without checking for adequate clearance between the oil pump pickup and the pan. SAM recommends between .250- and .375-inch of clearance, and set it at .300 inch on our 461.
A short-block is only as good as the cylinder heads that feed it, and the Edelbrock Performer RPM aluminum castings we bolted to our 461 offer a tremendous improvement in performance over the stock units. They feature 188cc intake ports, stainless steel 2.072/1.680-inch valves, 77cc fast-burn combustion chambers, and thick 5/8-inch decks. Although the ports retain their stock locations, the exhaust port floors have been raised to improve flow. Out of the box, they moved exactly as much air as advertised at 270/180 cfm. That said, one drawback of the factory Oldsmobile cylinder head architecture is its intake port location in relation to the valve angle. While a near-vertical 6-degree valve angle looks great on paper, they yield a sharp transition at the short-turn radius due to the head's relatively low intake port entrance location. By creating a more gradual transition at the short-turn and doing a performance valve job, SAM's students were able to boost airflow to 315/200 cfm. Chevy buffs might contend that so much airflow through a 188cc (before porting) intake runner seems like an awful lot, but there's good reason for this. "With Oldsmobile heads, the distance between the intake port entrance and the valve is very short. This means that the Edelbrock heads pack enough cross-sectional area to support well over 300 cfm of flow despite having a relatively small port volume," Massingill says. "A typical 23-degree small-block Chevy head, which has much longer runners, would need 220-235cc intake ports to flow in this arena. This simply reinforces why cross-sectional area is a more accurate way to gauge a head's flow potential than looking at the intake port volume, and why comparing the port volumes between different cylinder head platforms is a meaningless exercise." The Olds' COMP Xtreme Energy... The Olds' COMP Xtreme Energy 240/246-at-.050 hydraulic flat-tappet cam is ground on a tight 110-degree LSA, and boasts .541/.544-inch lift. Order up PN SK42-225-4 from Summit, and you'll get a set of lifters and a double-roller timing set as part of a bundled kit for $250. When it came time to select an intake manifold, conventional wisdom steered us toward an Edelbrock dual-plane design, however, the Olds gurus at Mondello Performance quickly corrected our errant path. Per the advice of Mondello's Lynn Welfringer, we opted for a single-plane Edelbrock Torker intake instead. "Oldsmobile motors are funny because they don't really make any more torque with a dual-plane manifold," he says. "An out-of-the-box Torker will actually do 12-13 numbers better in hp and torque than with a dual-plane. Our custom intake porting adds another 10 hp over that, for a total of 23 hp over a dual-plane. It's pretty amazing how well the Torker performs considering it was designed more than 30 years ago." Valvetrain
In keeping with our theme of simplicity and low cost, we skipped on the roller cam option and went with a COMP 240/246-at-.050 hydraulic flat-tappet stick. Although its less aggressive ramps most certainly give up some performance throughout the lift curve, we felt the rest of our engine package was good enough to compensate for it. In a 10.44:1 compression 461ci big-block, the cam's duration specs offered the rpm range we sought while preserving around-town streetability. Furthermore, the cam's .541/.544-inch valve lift allows retaining the valvesprings that came equipped on the Edelbrock heads, further reducing costs. Hitting the Pump
With a Holley 750-cfm 4150 carb bolted to the intake, and 93-octane pump gas flowing through the fuel lines, the 461 was ready to run. After warming the oil and water temperature up to operating range, the 461 belted out more than 500 hp and 500 lb-ft on the first pull. SAM's students and instructors achieved a maximum output of 514 hp at 5,500 rpm and 540 lb-ft of torque at 4,100 to 4,600 rpm with 91 carb jets and 32 degrees of timing. This exceeded our expectations by 14 hp and 15 lb-ft, but what was most surprising was the shape of the torque curve. More closely resembling a plateau than a peak, the 461's stout low and midrange torque will certainly help our heavy A-body Cutlass rocket out of the procession of low-speed corners it will encounter on the autocross.  The factory 455 rockers are...  The factory 455 rockers are marginal even in a mild build such as ours, so we ordered a set of 1.6:1 roller rockers from COMP Cams. They're built from a rugged aluminum alloy rated at 80,000-psi tensile strength, and their needle bearing trunnions can handle in excess of 350 pounds of open valvespring pressure.  The Edelbrock Performer RPM...  The Edelbrock Performer RPM heads come equipped with 1.460-inch springs that can handle up to .575 lift. They actuate 2.072/1.680-inch stainless steel valves.  Since an engine's crankshaft,...  Since an engine's crankshaft, camshaft, timing chain, and timing gears are manufactured to their own tolerances, degreeing a camshaft is an essential step in any performance engine build. This ensures that the cam is phased correctly in relation to the crankshaft. SAM students set our cam at a 109-degree installed centerline.  At $1,709 for a fully assembled...  At $1,709 for a fully assembled pair, Edelbrock's Performer RPM aluminum heads are an excellent value. They fit 400, 425, and 455ci Olds motors, and will easily outperform any factory big-block casting by at least 30 percent.  The flat 6-degree valve angle...  The flat 6-degree valve angle of the Olds' head results in a valve face that's nearly parallel to the deck surface, and a small 77cc fast-burn chamber. Likewise, the oval-shaped chambers yield dual quench pads, one on each side of the valves. Edelbrock has also repositioned the spark plug closer to the exhaust valve, and angled it at 45 degrees to improve burn efficiency. Not surprisingly, the 461 made maximum power with just 32 degrees of timing advance on the dyno.  Under the careful watch of...  Under the careful watch of SAM instructors, students worked the short-turn radius to smooth the sharp transition created by the head's flat valve angle and low intake port height. In conjunction with a performance valve job, the tweaks boosted flow from 270/180 cfm to 315/200 cfm.  The Edelbrock Torker intake...  The Edelbrock Torker intake combines the best of single-plane and dual-plane designs. Unlike many single-planes, it doesn't compromise low-end torque or require stepping up to a big, ugly hood. Mondello improves upon it further by massaging the runners, and installing a cone in the plenum, which is said to add swirl to the air/fuel mixture to even out fuel distribution to each cylinder. These tricks increase airflow by 17 percent, and boost hp by 10 numbers over a standard Torker.  To fuel the 461, we opted...  To fuel the 461, we opted for a 750-cfm Holley 4150 carb. Since the Torker intake features a spread-bore mounting flange, bolting the Holley up requires using an adapter plate.  Given the modest rpm our 461...  Given the modest rpm our 461 turns, we elected to externally balance the rotating assembly. The SFI-approved Professional Products harmonic damper includes a bolt-in counterweight to facilitate this. Circulating coolant in the big Olds is a GMB stock-replacement high-flow water pump.  To light off the 461, MSD...  To light off the 461, MSD set us up with one of its billet distributors. It's compatible with both small- and big-block Olds motors.  No one likes paying big bucks...  No one likes paying big bucks for custom headers, but fortunately Hooker makes a set of 1.75-inch long-tube headers (PN 3902-1HKR) that will fit early A-body chassis equipped with big-block Olds engines. They feature 5/16-inch flanges, 3-inch collectors, and 27-inch-long primaries. The headers wrap around a Mondello 7-quart oil pan. Since the 461 uses a Mondello high-volume pump, the larger oil pan capacity is a must.  After the 461 Olds churned...  After the 461 Olds churned out 514 hp and 540 lb-ft with the Holley carb, we decided to experiment by swapping it out for a 750-cfm Quadrajet. The prospect of making loads of power with a super-stealth production-style carb was very appealing. Although the air/fuel ratio was spot-on with the Q-jet in place, the motor lost 50 hp across the board, and peaked 500 rpm sooner. For obvious reasons, we bolted the Holley back on.  In addition to building performance...  In addition to building performance street and race motors, SAM's curriculum also involves learning how to operate an engine dyno. Instructors stress the importance of maintaining consistent fuel pressure, and oil and water temps from run to run to promote repeatability. The goal is to minimize hp variations between
1/2 to 1 percent from pull to pull.
| WHERE THE MONEY WENT |
| Item: |
Source: |
Summit PN: |
Cost: |
| 455 core |
eBay |
none |
$500 |
| Crank |
stock |
none |
$0 |
| Rods |
Eagle |
ESP-673503D |
$660 |
| Pistons |
SRP |
206072 |
$491 |
| Rings |
SRP |
S100S8-4155-5 |
$150 |
| Main bearings |
Clevite |
CLE-MS804P |
$60 |
| Rod bearings |
Clevite |
CLE-CB542P |
$72 |
| Cam bearings |
Clevite |
CLE-SH1354 |
$25 |
| Freeze plugs |
Sealed Power |
SLP-381-8020 |
$12 |
| Balancer |
Professional Products |
90022 |
$215 |
| Camshaft kit |
COMP Cams |
CCA-SK42-225-4 |
$250 |
| Lifters |
COMP Cams |
part of kit |
$0 |
| Timing set |
COMP Cams |
part of kit |
$0 |
| Timing cover |
stock |
N/A |
$0 |
| Rockers |
COMP Cams |
CCA-1044-16 |
$300 |
| Pushrods |
COMP Cams |
CCA-7183-16 |
$117 |
| Oil pan |
Mondello |
OP-805 |
$262 |
| Oil pump |
Mondello |
SP-765 |
$169 |
| Oil pump drive |
Mondello |
OD-260 |
$29 |
| Oil pump pickup |
Mondello |
PU-4 |
$42 |
| Oil restrictors |
Mondello |
R-104 |
$39 |
| Heads |
Edelbrock |
EDL-60519 |
$1,709 |
| Intake manifold |
Mondello |
2730 |
$659 |
| Valve covers |
Edelbrock |
EDL-4485 |
$46 |
| Head gaskets |
Edelbrock |
EDL-7340 |
$64 |
| Intake gasket |
Edelbrock |
EDL-7284 |
$14 |
| Exhaust gasket |
Edelbrock |
EDL-7238 |
$23 |
| Oil pan gasket |
Fel-Pro |
FEL-OS-30471-C |
$18 |
| Valve cover gasket |
Edelbrock |
EDL-7598 |
$23 |
| Head bolts |
Edelbrock |
EDL-8558 |
$95 |
| Main studs |
ARP |
ARP-185-5401 |
$60 |
| Damper bolt |
ARP |
ARP-180-2502 |
$23 |
| Intake bolts |
Edelbrock |
EDL-8514 |
$20 |
| Carb |
Holley |
HLY-04779C |
$435 |
| Carb studs |
ARP |
ARP-400-2414 |
$23 |
| Distributor |
MSD |
MSD-8566 |
$272 |
| Plug wires |
MSD |
MSD-31189 |
$77 |
| Water pump |
GMB |
130-1360 |
$60 |
| Parts total: |
$7,014 |
| MACHINE SHOP LABOR |
| Operation: |
Source: |
Cost: |
| Clean block |
SAM |
$85 |
| Bore/hone |
SAM |
$225 |
| Deck resurface |
SAM |
$150 |
| Cam bearings |
SAM |
$80 |
| Balancing |
SAM |
$100 |
| Turn crank |
SAM |
$100 |
| Head porting |
SAM |
$750 |
| Machining total: |
|
$1,490 |
| Grand Total: |
$8,504 |
| BY THE NUMBERS |
| 461ci Big-Block Olds |
| Bore: |
4.155 inches |
| Stroke: |
4.250 inches |
| Displacement: |
461 ci |
| Compression ratio: |
10.44:1 |
| Camshaft: |
COMP flat tappet |
| Cam duration: |
240/246 degrees at .050 |
| Valve lift: |
541/.544 inch |
| Rocker ratio: |
1.6:1 |
| Lobe separation: |
110 degrees |
| Installed centerline: |
109 degrees |
| Top ring: |
1/16 inch |
| Top ring gap: |
.026 inch |
| Second ring: |
1/16 inch |
| Second ring gap: |
.028 inch |
| Oil ring: |
3/16 inch |
| Pistons: |
SRP |
| Block: |
stock 455 Olds |
| Crankshaft: |
stock nodular iron |
| Rods: |
Eagle 6.735 inch steel |
| Main journal: |
2.988 inches |
| Main bearing clearance: |
.0035 inches |
| Rod journal: |
2.488 inches |
| Rod bearing clearance: |
.0027 inch |
| Bearings: |
Clevite |
| Cylinder heads: |
Edelbrock Performer RPM |
| Intake valve diameter: |
2.072 inches |
| Exhaust valve diameter: |
1.680 inches |
| Intake manifold: |
Edelbrock Torquer |
| Carburetor: |
Holley 750 cfm |
| Ignition: |
MSD |
| DYNO DATA |
| RPM |
TQ |
HP |
| 3,000 |
494 |
282 |
| 3,100 |
489 |
289 |
| 3,200 |
487 |
297 |
| 3,300 |
488 |
306 |
| 3,400 |
490 |
317 |
| 3,500 |
494 |
329 |
| 3,600 |
501 |
344 |
| 3,700 |
512 |
361 |
| 3,800 |
522 |
378 |
| 3,900 |
529 |
393 |
| 4,000 |
535 |
407 |
| 4,100 |
540 |
422 |
| 4,200 |
540 |
432 |
| 4,300 |
540 |
442 |
| 4,400 |
540 |
451 |
| 4,500 |
540 |
462 |
| 4,600 |
540 |
473 |
| 4,700 |
538 |
481 |
| 4,800 |
533 |
487 |
| 4,900 |
528 |
493 |
| 5,000 |
522 |
497 |
| 5,100 |
516 |
501 |
| 5,200 |
511 |
505 |
| 5,300 |
505 |
509 |
| 5,400 |
499 |
513 |
| 5,500 |
491 |
514 |
| 5,600 |
481 |
513 |
| 5,700 |
471 |
511 |
| Ave: |
513 |
425 |
|
|
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