1971 Pontiac Formula 400
Engine
Stock Displacement: 400 (actual 400.18)
Block modifications: trimming of flange castings by lifter cross over for better oiling
Freeze plugs: brass
Displacement after bore: 406 (.030-inch over)
Bore: 4.12
Stroke: 3.75
Main Size: 3.00
Main Caps: stock 2 bolt
Rotating assembly: Stock
Crank: Stock 3.75
Rods: Stock (Length)
Bearings: Federal Mogul Cam FEM-1220M, Main FEM4040M, Rod FEM-8-7050CH
Pistons: unknown .030-inch over aluminum stock type flat top
Rings: Moly model SLP-E-299K030 from Summit/Sealed Power brand
Timing Chain and Gear: Comp Cam model 2112 stock chain gear type
Oil pump: Melling MEL-10541, shaft MEL-IS-54A
Camshaft: Summit model SUM-2801 214 / 224 duration at .05” lift with 1.5 rockers,
advertised 272 / 282, 112 lobe separation
Lifters: Comp Cam model 852-16
Push Rods: Comp Cam CCA-7851-16, length 9.136”, 5/16” diameter
Rocker Arms: Harland Sharp 1.50 full roller rocker model CSP-S6001
Clylinder heads: Stock 1971 96cc heads
Cylinder head modifications: trimming of casting flanges for better oiling, light porting of exhaust, light porting of intake openings and push rod bulge
Rocker arm studs: 7/16” (big block Chevy type) ARP Model ARP-135-7101, poly-lock 7/16” by ARP model ARP-300-8245
Valves: Ferrea stainless steel valves 4.98” length; 1.77 exhaust model F5062, intake 2.11 model F5065
Valve springs: dual springs, Crower model 68404
Valve retainers: Comp Cam 10 degree model CCA-740-16
Compression ratio: 8.2-1
Fuel / intake
Carburetor: Stock 1971 Rochester 704163 750 CFM
Intake: stock 1971 455 HO aluminum intake with cast iron exhaust crossover (blocked)
Octane: pump gas 91 octane
Air cleaner: Stock ram air cleaner
Exhaust
Mufflers: Dynomax, dual mufflers
Tail pipes: 2.5” diameter
Exhaust Manifolds: Stock ram air III D ports
Cooling
Radiator: OEM style from NPD; Aluminum. 160 degree thermostat
Drivetrain
Axle: 3.75
Tries: BF Goodrich 235/60 R15, Rally 15 x 7 rims
Traction bars: Lakewood
Transmission: 4 speed, Muncie M21 close ratio
Clutch: Ram clutch, 10 1 /2” diameter
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