GM Regular Production Options (RPO)

GM Regular Production Options (RPO) Codes codes are frequently used to describe a particular engine combination in a particular vehicle. Some RPO's used the same number in different years but motors might have slightly different equipment.

L-19 1988-1990, Mark IV 454/230HP, light duty trucks, 4-bolt Mark IV block, cast crank, cast pistons, hydraulic cam, open chamber oval port heads, compression 8.25:1

1991-1995, Gen V 454/230HP, light duty Trucks, 4-bolt block, cast crank, cast pistons, hydraulic cam, Gen V oval ports open chamber heads, compression: 8.25:1

L-34 1966-1969, 396/350,360HP, 2-bolt ('66: 4) block, steel crank, cast pistons, closed chamber oval ports heads , High lift hydraulic cam, compression 10.25:1, Holley carb ('66-'68), Quadrajet carb ('69-'69), cast hi-rise intake

1970, 402/350HP, same as above but bigger bore and Quadrajet carb, 2-bolt block

L-35 1965-1967, 396/325HP, 2-bolt block, steel crank, cast pistons, closed chamber oval port heads, hydraulic cam, compression: 10.25:1, Holley 4 barrel carb, cast hi-rise intake

1968-1969, 396/325HP, 2-bolt block, cast crank, cast pistons, closed chamber oval port heads, hydraulic cam, compression: 10.25:1, Quadrajet carb, cast intake

L-36 1966-1969, 427/385HP or 390HP, 2-bolt block, steel crank, cast pistons, closed chamber oval port heads, High-lift hydraulic cam, compression: 10.25:1, Holley or Quadrajet carb, cast intake, aluminum Low-rise Quadrajet intake on 1968-1969 Corvettes

L-66 1969, 396/265HP, 2-bolt block, steel crank, cast pistons, closed chamber oval port heads, hydraulic cam, compression: 9.0:1, 2 barrel carb, cast intake

L-68 1967-1969, 427/400HP Corvettes, same as L-36 but with three 2 barrel carb, cast intake

L-71 1967-1969, 427/425HP or 435HP Corvettes, same as L-72 but three 2 barrel Holley carb, aluminum rectangular port intake

L-72 1966-1968, 427/425HP, 4-bolt block, steel "Tuftride" crank, forged pistons, closed chamber rectangular port cast heads, mechanical cam, compression: 11.1:1, Holley 800cfm carb on aluminum hi-rise intake

L-78 1965-1969, 396/375HP, 4-bolt block, steel "Tuftride" crank, forged pistons, closed chamber heads with rectangular ports, mechanical cam, compression: 11.0:1, Holley 800cfm carb, aluminum hi-rise intake

1965, 396/375HP, Z-16 Chevelle, same as above, but with high-lift hydraulic cam, 780cfm Holley carb

1965, 396/425HP, Corvette and Passenger Cars, same as 396/375HP L-78 with mechanical cam

1970, 402/375HP, same as 1965-1969 396/375HP, but bigger bore, mechanical cam

L-88 1967-1969 427/430HP Corvette, 4-bolt block, steel "Tuftride" crank, 7/16" "dot" rods, forged "floating pin" pistons, 1/16" pistonrings, mechanical crank, closed chamber rectangular ports aluminum heads (1967-1968), open chamber rectangular ports aluminum heads (1969), 7/16" pushrods, compression: 12.5:1, Holley 850cfm carb on aluminum hi-rise intake

L-89 1968-1969 396/375HP, same as L-78, but with optional closed chamber rectangular port aluminum heads for Nova and Camaro

1968-1969 427/425HP Corvette, same as L-71, but with optional closed chamber rectangular port aluminum heads

LS-1 1969 427/335HP Passenger Car, 2-bolt block, cast crank, cast pistons, closed chamber oval port heads, hydraulic cam, compression: 10.25:1, Quadrajet carb, hi-rise cast intake

LS-3 1970 402/330HP, 2-bolt block, cast crank, cast pistons, closed chamber oval port heads, hydraulic cam, compression: 10.25:1, Quadrajet carb, Lo-rise cast intake

1971 402/300HP, same as above, but with open chamber oval port heads, compression: 8.5:1

1972 402/240HP, with dual exhaust or 402/210HP with single exhaust, otherwise the same as 1971 LS-3

LS-4 1970 454/345HP, 2-bolt block, steel crank, cast pistons, hydraulic cam, closed chamber oval port heads, compression: 10.25:1, Quadrajet carb on cast intake

1973-1974 454/215HP, 235HP, 245HP, 270HP, same as above, but 2-bolt block, cast crank, open chamber oval port heads, compression: 9.0:1

LS-5 1970 454/360HP or 390HP, 2 or 4-bolt block, steel crank, cast pistons, hydraulic cam, closed chamber oval port heads, compression: 10.25:1, Quadrajet carb on Low-rise cast intake

1971 454/365HP, same as above, but with open chamber oval port heads, compression: 8.5:1

1972 454/240HP with single exhaust or 270HP with dual exhaust, otherwise it is the same as 1971 LS-5 454

LS-6 1970 454/450HP Chevelle, 4-bolt block, steel "Tuftride" crank, 7/16" "dot" rods, forged "floating Pin" pistons, closed chamber rectangular port heads, compression: 11.0:1, mechanical cam, Holley 800cfm carb on aluminum Low-rise intake

1971 454/425HP Corvette, same as above, but with open chamber rectangular port aluminum heads, Monte Carlo and Chevelle have cast open chamber rectangular port heads, compression: 9.0:1

LS-7 454/465HP never factory installed in a vehicle, it became available in 1970 as an "over the counter" crate motor or could be built with "over the counter" parts, 4-bolt block, steel "Tuftride" crank, 7/16" "dot" rods, forged "floating pin" pistons, 1/16" pistonrings, mechanical cam, aluminum open chamber rectangular port heads, compression: 12.5:1, 3/8" pushrods, Holley 850cfm carb on aluminum hi-rise intake, original intended for Corvette

ZL-1 1969 427/430HP, Camaro and Corvette, same as L-88 except ZL-1 used an aluminum block, only installed in 2 Corvettes and 69 Camaros, some engines sod "over the counter"

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