To begin with, Miller recommends going with an 850 HP Holley carburetor to ensure plenty of cfm to feed those hungry cylinders along with either an Offenhauser Port-O-Sonic or Edelbrock Torker single-plane intake. The single-plane might cost a little low-speed torque, but with an engine this big, you can afford to move the torque curve up a little.
The Olds cast-iron "C" heads with stock 2.07/1.71-inch valves and a 79cc combustion chamber offer the best potential. This will create around 9.75:1 compression with a typical head gasket and dished piston. Miller says you'd have to plan on substantially porting these heads to create sufficient flow to make this 500hp number, but it is possible. Another alternative is to look at the new Bulldog aluminum cylinder head that offers substantially better flow over even the ported iron heads. The heads aren't cheap at $2,195, available through Dick Miller Racing, but now you're working with a brand-new set of aluminum heads.
Miller offers his own custom cam that works very well with this combination, but he'd rather not publish its specs. A Lunati single-pattern cam that comes very close, according to Miller, offers 295 degrees of advertised duration with 245 degrees at 0.050-inch tappet lift, a valve lift of 0.569-inch, and a lobe separation angle of 108 degrees. With the Olds' long stroke, idle quality is still decent, although this should not be considered a daily driver type engine.
Miller also suggests Kooks 171/48-inch headers with 311/42-inch collectors and a 3-inch exhaust system back through Magnaflow 3-inch mufflers and 211/42-inch tailpipes. The Kooks headers offer excellent collector design and are designed to fit the popular '64-'67 Cutlass body style. According to Miller, this engine should make around 570 to 580 lb-ft of torque and 500-plus-hp without spinning the engine to extreme rpm, especially since the larger main bearings are not designed to handle high rpm.
The Olds is renowned as a torque-maker, so it's best to capitalize on those qualities.
SpecsDisplacement: 455 ci, bore x stroke-4.125x4.250Carburetor: 850 HP HolleyIntake: Offenhauser Port-O-Sonic PN 6109, Edelbrock Torker PN 7112Heads: Olds iron "C" heads, 2.07/1.71-inch valvesCompression: 9.75:1Camshaft: Lunati PN 07183 hydraulic flat-tappet 295 adv., 245 degrees @ 0.050, 0.569-inch lift 108-degree lobe separation angleHeaders: Kook's 171/48-inch primary pipeExhaust: 3-inch exhaust, Magnaflow mufflers
Chevy 454There are those who speak only in Chevy Rat motor terms when it comes to making power and torque. We talked to Super Gas racer and Flowmaster dyno master Kevin McClelland who offered his ideas on street Rat power. McClelland says the stock iron rectangle port castings can be made to work but focus on the exhaust side. The intake ports are already too big, but larger 2.250/1.880-inch valves are a good idea and pocket work will help. There are several aftermarket aluminum Rat heads to choose from, including the new 305cc AFR castings, and the 320cc World Products Jenkins signature head with 2.300-inch intake valves are excellent.
Even though this is a pump gas street engine, McClelland suggests a fast mechanical flat tappet cam with a duration of 232/240 at 0.050 with a 110-degree lobe separation angle and lift around 0.550-inch lift. Comp Cams grinds a XS268 Xtreme Energy mechanical that very closely fit this spec.
On the intake side, the Edelbrock Performer RPM Air Gap is the best choice combined with an 850-cfm Demon or Holley HP carb. Try to keep the compression under 10:1 so it will be friendly with pump gas. Kevin suggested 171/48-inch headers for peak power, or 131/44-inch headers that will help the torque. For an exhaust, a 3-inch system will make the most power, but it will also be the loudest. With that, you're ready to rumble.