Back in the good old days when there was no replacement for raw displacementand what was good for General Motors was good for America, the General produced no less than three distinct 455ci engines: a Buick, an Olds, and a Pontiac. All were unique designs, sharing only a common rear block-face bolt pattern. In their day, the General's 455s were stump-pulling torque monsters, designed to effortlessly pull luxo heavy metal in style and comfort. But is any one 455 clearly superior to its sisters? To find out, Car Craft, in conjunction with Westech Performance, has decided to build up an example of each 455 using commonly available off-the-shelf performance parts. Subject to real-world parts availability, we'll build each motor as identically as possible using modern high-flow aluminum heads, about a 10.0:1 compression ratio, an aggressive (yet still streetable) Comp Xtreme Energy XE274H hydraulic flat-tappet cam, Hooker Super Competition headers, a dual-plane intake manifold, and a Speed Demon 750-cfm double-pumper carb. Although the engines will use a good cam and heads, we'll assemble the bottom ends just like an average car crafter would: no exotic parts or niche tricks-just good machining practice, premium Federal-Mogul bearings, Speed-Pro piston rings and forged pistons, and Fel-Pro gaskets. This month we'll showcase the buildup and test of a '72 455 Olds. In coming months, we'll pound a Pontiac and bang on a Buick. Which one will end up the top dog? Your guess is as good as ours. Stay tuned.
Bottom End
Westech turned the engine over to Dougan's Engine Rebuilding for inspection, hot-tanking, and machine work. The block was surfaced to square-up the decks, then align-honed to true up the main-bearing bores for the stock crank, which was cross-drilled for improved oiling and ground 0.010-inch undersize on both the main and rod journals. The junkyard block had already been rebuilt once before, so it was bored 0.060-over, then final-honed with a torque plate. After the stock Olds rods passed magnetic-particle inspection, they were reconditioned, fitted with new ARP bolts, and pin-fit to the pistons.
Next, it was back to Westech where the balanced rotating assembly was assembled with Federal-Mogul H-14 competition-series main and rod bearings, which have a unique lining bonded to an extra-high-strength steel backing. The rings are a standard-gap premium Speed-Pro set (51/464-inch high-strength plasma-moly ductile-iron top; 51/464-inch cast-iron second; and 31/416-inch standard-tension SS-50 oil control). Unlike standard rebuilder rings that often come gapped way too wide, the Speed-Pro set was factory-gapped to the recommended minimums.
The front oil-galley plug with the small 0.040-inch bleed hole installs on the passenger side. The hole lubes the timing chain when the motor is running, so if you need to replace it, make sure you get one with the hole or drill it yourself. | 
A two-piece 429/460 Ford rubber rear seal replaced the standard leak-prone rope seal. For added leak resistance, the seal halves were offset from the bearing cap and block parting lines. |
Nothing fancy about the piston-and-rod combo-just reconditioned factory rods fitted with ARP bolts, Speed-Pro rings, and Speed-Pro dished forged pistons retained by press-fit piston pins. | |
Cam And Valvetrain
Westech stuffed the latest Comp Cams hydraulic flat-tappet street cam in the Olds: an Xtreme Energy grind with an aggressive lobe design that produces better throttle response and top-end power than other cams with equivalent 0.050-inch tappet-lift durations, even while maintaining increased engine vacuum. For better valvetrain stability, the Edelbrock heads replace the stock Olds nonadjustable pedestal-mount setup with 71/416-inch screw-in studs and guideplates set up for 31/48-inch-od hardened pushrods. This requires custom-length pushrods and non-Olds rocker arms. With Edelbrock's stock-height valve covers, it was necessary to double-stack valve-cover gaskets to provide clearance for the Comp Cams aluminum roller rockers.
Camshaft Specifications
Manufacturer: Comp Cams
Part No.: 42-224-4
Grind: XE274H-10
Type: Hydraulic flat-tappet
Duration at 0.006-inch tappet lift: 274 int./286 exh.
Duration at 0.050-inch tappet lift: 230 int./236 exh.
Valve lift (1.60:1 rockers): 0.520" int./0.523" exh.
Lobe displacement angle (LDA): 110
Installed intake centerline: 106
Combined with a cross-drilled crank, Speed-Pro's black-oxide-coated high-volume oil pump ensures adequate lubrication of the big Olds bearings. | 
The desirable Olds nodular-iron crank has an "N" (shown) or "CN" cast on the No. 1 counterweight. |
The cam came as part of Comp's "SK" kit, which also includes lifters and a timing set (in this case, a Magnum double-roller chain). Don't forget to install the Olds fuel-pump eccentric and crankshaft oil slinger. | |