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BIG-BLOCK CASTING NUMBERS

One of the fun things about restorations and buying Chevy engines, blocks and heads is the casting number search.

Back in the early 1980s, no reference material was available other than what was listed in a Chilton’s or Motor’s manual. We were one of the first to seek out horsepower codes, then casting numbers. Many have followed suit and have produced a number of different reference manuals. Here are our personal big-block head and block casting number lists. We feel it is extremely accurate and is as exact as we can make it. After all, we use both ourselves at every wrecking yard, swap meet and garage sale we visit. For sure, we do not leave home without them!

ENGINE BLOCK

NUMBER
 ENGINE
YEAR
DECK HEIGHT
340220 427 1972-76 10.2
345014 454 1974-86 9.8
346236 454 1974-76 9.8
359070 454 1970-76 9.8
361959 454 1973-85 9.8
364776 427 1968-84 10.2
364779 366 1968-88 10.2
473478 427 1968-84 10.2
3855061 396 1965-67 9.8
3855961 396 1965-67 9.8
3855962 396 1965-66 9.8
3855977 366 1966-67 10.2
3866961 396 1966-69 9.8
3869942 427 1966-69 9.8
3873858 396 1966 9.8
3902406 396 1965-67 9.8
3903466 396 1965-67 9.8
3904351 427 1966-69 9.8
3904354 366 1966-76 10.2
3916319 366 1968 10.2
3916321 427 1966-69 9.8
3916323 396 1967-68 9.8
3916328 396 1965-67 9.8
3918319 366 1966-70 10.2
3935439 427 1966-69 9.8
3935440 396 1968 9.8
3937724 366 1968-85 10.2
3937726 427 1968-84 10.2
3955270 427 1969 9.8
3955272 396 1968-69 9.8
3955274 366 1968-85 10.2
2955276 427 1968-84 10.2
3963512 427 1969-71 9.8
3963512 454 1970-76 9.8
3963513 454 1973-76 9.8
3965440 396 1968-69 9.8
3965449 396 1968-69 9.8
3965440 396 1968 9.8
3969854 396/402 1969-72 9.8
3969854 454 1969-72 9.8
3969858 427 1968-84 10.2
3999289 454 1972-78 9.8
3999290 402 1972 9.8
3999293 366 1968-85 10.2
3999294 427 1968-84 10.2
6272176 366 1968-76 10.2
6272177 402 1972-73 9.8
6272181 427 1973-76 10.2
14015445 454 1975-87 9.8
 Deck Height:     Passenger Car = 9.8     Truck = 10.2

CYLINDER HEADS BY CASTING NUMBER

NUMBER
ENGINE
YEAR
CHAMBER CC
REMARKS
3856208 396/427 1965-67 109 Hi-Perf/Lg Port
3872702 396 1965-66 96 325 and 360 hp
3872702 427 1966 96 390 hp
3873702 396 1966 96 325 and 350 hp
3873858 396 1965-66 109 Hi-Perf/Lg Port
3873858 427 1966 109 Hi-Perf/Lg Port
3904390 396 1965-66 96 325 and 350 hp
3904390 427 1966 96 390 hp
3904391 396 1965-66 109 Hi-Perg/Lg Port
3904391 427 1966 109 Hi-Perf/Lg Port
3904392 427 1967 109 Aluminum
3909802 396 1965-66 96 325 and 350 hp
3909802 396 1966
3917215 396 1965-68 96 325 and 350 hp
3917215 427 1966-68 96 390 hp
3919839 396/427 1968-69 105 Hi-Perf/Lg port
3919840 396/427 1965-69 105 Hi Perf/Lg Port
3919842 396/427 1968-69 107 Aluminum
3931063 396 1965-69 96 325 and 350 hp
3931063 427 1966-69 96 385 and 390 hp
3933149 396 1969-70 122 265 hp
3946074 27 1969 118 Aluminum
3964280 427/454 1965-70 101
3964290 396/402 1966-69 96 325 and 350 hp
3964290 427 1966-69 96 390 hp
3964290 454 1970 96 360 hp
3964291 396/402 1965-70 108 Hi-Perf/Lg Port
3964291 454 1970 108 Hi-Perf/Lg Port
3964292 454 1970 108 Hi-Perf/Lg Port
3965198 396 1969 100
3993820 402/454 1971 113 300 and 365 hp
3994026 454 1971 103 Hi-Perf/Lg Port
3999241 402/454 1971-72 105 365 hp
6258723 454 1971 103 Hi-Perg/Lg Port
6272292 402/454 1972 107 240 and 270 hp
6272990 454 1971 103 Hi-Perf/Lg Port
10051128 454 1990-94 72 Bow Tie
14011077 454 1989-94 118 Replacement
14044861 454 1989-94 105 Bow Tie

BIG-BLOCK RPO NUMBERS: 1965-1976

396 TURBO-JET (1965-69)
L-34 1966-67 Rated at 350hp and 360hp with Holley carburetor.
1968-69 Quadrajet carburetor came onboard. Cam: High-lift performance hydraulic. Heads: Oval intake ports. Compression ratio: 10.25:1. Crankshaft: Forged steel. Block: Mostly two-bolt main caps; some four-bolt main caps in early Chevelles. Can make 500 hp with big cam, intake, carb and headers.
L-35 1965-69 325hp, smooth-idle, torque engine. Heads: Oval intake ports. Cam: Low-lift torque-type. Mostly Quadrajet carb, but some had a Holley. Crankshaft: Forged steel in ’66-’67 engines; nodular iron in ’68-’69. Compression: 10.25:1. Block: Two-bolt main bearing caps. Can make 500 hp with big cam, intake, carb and headers.
L-66 1969 Rare two-barrel 396. Small-port heads; low-rpm torque engine; 9.0:1 compression; two-bolt main bearing caps; nodular-iron crankshaft.
L-78 1965-69 375 hp in ’65 Chevelle with performance hydraulic camshaft; 425 hp in Corvette and big-car with solid lifter camshaft. Carb: 800cfm Holley. Heads: Large rectangle-type intake port; power to 7,200 rpm. Block: Four-bolt main bearing caps. Compression: 11.0:1/forged pistons. Crankshaft: forged steel/tuft-rided.
L-89 1968-69 It is an L-78 with aluminum, closed-chamber heads.
402 TURBO-JET (1970-72)
L-34 1970 Same as 396, but with a 0.032-inch overbore.
L-78 1970 Same as 396, but with a 0.032-inch overbore.
LS3 1970-71: Same as L-35 396. Rated at 330 hp in 1970. 8.50:1 compression in 1971 dropped rated gross horsepower to 300. Block: Two-bolt main bearing caps. Crankshaft: Nodular iron. Camshaft: Low-lift hydraulic.
LS3 1972 Rated at 240-net-hp with dual-exhaust system. Rated at 210-net-hp with single exhaust.
427 TURBO-JET (1966-69)
L-36 1966-69: Rated at 385 hp and 390 hp with different exhaust systems. Mostly Quadrajet carb, some Holley. Compression: 10.25:1. Heads: Oval intake ports. Camshaft: High-performance hydraulic. Block: Two-bolt main bearing caps. Forged steel crankshaft.
L-68 1967-69   Same as L-36, except for Holley tri-carb; two-barrel induction system on oval-port aluminum intake manifold.
L-72 1966-68 Rated at 425 hp. Carb: 800cfm Holley on aluminum high-rise intake manifold with plenum divider. Camshaft: Solid lifter. Compression ratio: 11.0:1/forged pistons. Block: Four-bolt main bearing caps. Crankshaft: Forged steel, tuft-rided. Considered Chevy’s best Street big block due to its driveability and rev-ability.
L-71 1967-69 Same as an L-72, except for Holley tri-carb; two-barrel induction system on rectangle-port aluminum intake manifold.
L-89 1968 Same as L-71, except for aluminum, closed-chamber heads.
L-88 1967-69 Factory race engine. Compression: 12.5:1/forged pistons with floating wrist pins. Camshaft: Ultra-radical solid lifter. Carburetor: 850cfm Holley. Said to have aluminum heads (open-chamber in 1969). Crankshaft: Forged steel, tuft-rided. Larger 7/16-inch-diameter pushrods. High-rise, open-plenum intake manifold.
LS1 1969 Rated at 335 hp. Quadrajet carburetor. Oval-port heads, low-lift hydraulic camshaft. Compression: 10.25:1. Block: Two-bolt main bearing caps. Crankshaft: Nodular iron.
ZL-1 It was a COPO, not RPO.
454 TURBO-JET
LS4 1970 Rated at 345 hp with Quadrajet carburetor. Camshaft: Low-lift hydraulic. Heads: Oval intake ports. Compression: 10.25:1. Block: Said to have four-bolt main bearing caps. Crankshaft: Said to be forged steel.
LS4 1973-76 Rated from 270-net-hp to 215-net-hp in different chassis. Quadrajet carburetor. Low-lift hydraulic camshaft. Heads: Oval intake ports. Compression: 9.0:1. Block: Two-bolt main bearing caps. Crankshaft: Nodular iron.
LS5 1970 Depending on chassis, rated at either 360 hp or 390 hp. Quadrajet carburetor. High-lift hydraulic camshaft. Heads: Oval intake ports. Compression: 10.25:1. Block: Four-bolt main bearing caps. Crankshaft: Forged steel.
LS5 1971 Rated at 365 hp. Heads: Oval intake ports with open combustion chambers for less compression ratio (8.5:1).
LS5 1972 Same as 1971, but rated at 270 hp with dual exhaust and 230 hp with single exhaust.
LS6 1970 Officially rated at 450 hp. Compression: 11.0:1/forged pistons. High-lift, solid-lifter camshaft. Heads: Rectangle intake ports. Block: Four-bolt main bearing caps. Crankshaft: Forged steel, tuft-rided. Carburetor: 800cfm Holley.
LS6 1971 Rated at 425 hp with iron open-chamber heads. Compression: 9.0:1. Otherwise, same as 1970 LS6.
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