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Visually Identifying GM V-8 Engines, Handy Quick Reference

I. Distributor at the front of the engine, tilted to the drivers side Buick AND Cadillac - starter on passenger side, oil filter at front on passenger side

A-1. 4 bolt valve covers Buick / Rover small block family, integrated aluminum timing cover. All exhaust runners are discrete. All of these displacements have different deck heights and cannot swap intakes with each other. Spacer plates have been fabricated to use 215 intakes on 300 blocks.
1. Aluminum Block and Heads, test with magnet. Also found in the 1961-63 Pontiac Tempest.
215 - 3.500” x 2.800”, 1961-63, Buick Blue-Green
2. Aluminum Heads, Iron Block, test with magnet
300 - 3.750” x 3.400”, 1964-64, Buick Blue-Green
3. Iron Block and Heads, test with magnet
300 - 3.750” x 3.400”, 1965-67, Buick Medium Red
340 - 3.750” x 3.850”, 1966-67, Buick Medium Red

A-2. 4 bolt valve covers Cadillac big block family, integrated aluminum timing cover. Center exhaust runners are siamesed. First Cadillac use of ‘Buick style’ timing cover introduced in 1961.
390 - 4.000” x 3.875”, 1963-63, short deck engine
429 - 4.125” x 4.000”, 1964-67, oversize 1963 390

B-1. 5 bolt valve covers - 2 bolts on top rail of valve cover, 3 on bottom Buick / Rover small block family, integrated aluminum timing cover. Factory installed in Oldsmobile applications ONLY. 4 extra head bolts on each cylinder bank. Heads can be swapped to Buick / Pontiac / Rover as long as all of the attendant valve train goes with it.
1. Aluminum Block and Heads, test with magnet.
215 - 3.500” x 2.800”, 1961-63, Buick Blue-Green(?)

B-2. 5 bolt valve covers - 3 bolts on top rail of valve cover, 2 on bottom Buick big block family, integrated aluminum timing cover, displacement stamped on top of the bellhousing. All engines in this family used 1 x 4v carburet ion except for the very rare 1 x 2v available in 1974 only.
1. Ribs on valve covers are side to side, relief area in middle for displacement label
400 - 4.0400” x 3.900”, 1967-69, Buick Medium Red
430 - 4.1875” x 3.900”, 1967-69, Buick Medium Red
2. Ribs on valve covers are front to back, no relief area
455 - 4.3125” x 3.900”, 1970-74, Buick Dark Red
455 - 4.3125” x 3.900”, 1975-76, Oldsmobile Blue

C. 6 bolt valve covers Buick small block family; integrated aluminum timing cover, the 350 does NOT share the intake / exhaust valve arrangement of the other members of this family so heads, cams, and manifolds CANNOT be swapped to the 340 without great difficulty / expense and without swapping the entire top end of the motor. Deck height is taller than small block Buicks with less than 340 cubic inches.
350 - 3.800” x 3.850”, 1968-69, Buick Medium Red
350 - 3.800” x 3.850”, 1970-76, Buick Dark Red
350 - 3.800” x 3.850”, 1977-81, GM Corporate Blue

D. 9 bolt valve covers Cadillac modern big block family, integrated aluminum timing cover, these are all variations of the 472.
368 - 3.800” x 4.060”, 1980-82, GM Corporate Blue
368 - 3.800” x 4.060”, 1983-84, GM Corporate Black
425 - 4.082” x 4.060”, 1977-79, GM Corporate Blue
472 - 4.300” x 4.060”, 1968-74
500 - 4.300” x 4.304”, 1970-76



II. Distributor at the rear of the engine (next to the firewall)

A. Buick Nailhead engine family, the valve covers are horizontal or level with the ground unlike any other production engine, starter on driver side, oil filter at rear on passenger side. These are all variations of the 322.
264 - 3.625” x 3.200”, 1954-55, Buick Pale Green
322 - 4.000” x 3.200”, 1953-56, Buick Pale Green
364 - 4.125” x 3.390”, 1957-58, Buick Pale Green
364 - 4.125” x 3.390”, 1959-61, Buick Blue-Green
401 - 4.188” x 3.640”, 1959-66, Buick Blue-Green
401 - 4.188” x 3.640”, 1966-66, Buick Medium Red, GS Skylark
425 - 4.313” x 3.640”, 1963-65, Buick Blue-Green
425 - 4.313” x 3.640”, 1966-66, Buick Medium Red

B. Cadillac vintage OHV family, starter on passenger side, taller decks than the 63 and newer engines. Distributor and Oil pump at rear of block.
331 - 3.8125” x 3.625”, 1949-1951, 2v carb
331 - 3.8125” x 3.625”, 1952-1955, 4v carb
331 - 3.8125” x 3.625”, 1952-1955, 2 x 4v carb, Eldorado
365 - 4.000” x 3.625”, 1956-1958, 4v carb
365 - 4.000” x 3.625”, 1956-1957, 2 x 4v carb, Eldorado
365 - 4.000” x 3.625”, 1958-1958, 3 x 2v carb, Eldorado
390 - 4.000” x 3.875”, 1959-1962, 4v carb
390 - 4.000” x 3.875”, 1959-1960, 3 x 2v carb, Eldorado

B. Chevrolet - Distributor passes through the intake manifold. 4 bolt valve covers. Starter on passenger side. Oil filter at rear on drivers side.

D. Oldsmobile - Oil filler tube is at front of engine, feeds into timing cover. Distributor does NOT pass through the intake manifold. 10 bolt valve cover on almost all engines although some covers only have bolts in 5 positions. Valve cover is shaped liked a trapezoid with the top rail of the cover being longer than the bottom rail. Starter on driver’s side.
1.14” between the heads at the base of the intake manifold - big block
2.12” between the heads at the base of the intake manifold - small block

E. Pontiac - Intake separated from intake valley cover (also true of 49-64 Oldsmobile’s). Externally Pontiacs are the same, the distinction between ‘Big’ and ‘Small’ block is made on the basis of the Main Bearing diameter ( ‘Big’ = 3.250”, ‘Small’< = 3.000” ).
1.1966 and earlier - 2 freeze plugs per side of block
a. Small Blocks w / 3.000” diameter main bearings or smaller
287 - 3.750” x 3.250”, 1955, 2v carb
287 - 3.750” x 3.250”, 1955, 4v carb
317 - 3.9375” x 3.250”, 1956, 2v carb
317 - 3.9375” x 3.250”, 1956, 4v carb
317 - 3.9375” x 3.250”, 1956, 2 x 4v carb
326 - 3.7187” x 3.750”, 1964-66, 2v carb
326 - 3.7187” x 3.750”, 1964-66, 4v carb
336 - 3.780” x 3.750”, 1963, 2v carb
336 - 3.780” x 3.750”, 1963, 4v carb
347 - 3.9375” x 3.562”, 1957, 2v carb
347 - 3.9375” x 3.562”, 1957, 4v carb
347 - 3.9375” x 3.562”, 1957, 3 x 2v carb
347 - 3.9375” x 3.562”, 1957, Fuel Injection, Bonneville
370 - 4.0625” x 3.562”, 1958, 2v carb
370 - 4.0625” x 3.562”, 1958, 4v carb
370 - 4.0625” x 3.562”, 1958, 3 x 2v carb
370 - 4.0625” x 3.562”, 1958, Fuel Injection, Bonneville
389 - 4.0625” x 3.750”, 1959-66, 2v carb
389 - 4.0625” x 3.750”, 1959-66, 4v carb
389 - 4.0625” x 3.750”, 1959-66, 3 x 2v carb
b. Big block w / 3.250” diameter main bearings
421 - 4.094” x 4.000”, 1961-63, 2 x 4v carb
421 - 4.094” x 4.000”, 1962-66, 4v carb
421 - 4.094” x 4.000”, 1963-66, 3 x 2v carb
2. 1967 and after - 3 freeze plugs per side of block
a. Small Blocks w / 3.000” diameter main bearings
265 - 3.750” x 3.000”, 1980-81, 2v carb
301 - 4.000” x 3.000”, 1977-79, 2v carb
301 - 4.000” x 3.000”, 1979-81, 4v carb
301 - 4.000” x 3.000”, 1980-81, 4v carb, TTA or Formula
326 - 3.7187” x 3.750”, 1967, 2v carb
326 - 3.7187” x 3.750”, 1967, 4v carb
350 - 3.876” x 3.750”, 1968-77, 2v carb
350 - 3.876” x 3.750”, 1968-69, 4v carb
400 - 4.120” x 3.750”, 1967-76, 2v carb
400 - 4.120” x 3.750”, 1967-79, 4v carb
b. Big blocks w / 3.250” diameter main bearings
421 - 4.094” x 4.000”, 1967, 4v carb
428 - 4.121” x 4.000”, 1968-69, 4v carb
455 - 4.152” x 4.210”, 1970-76, 4v carb

Handy Quick Reference!

I. Distributor at the front of the engine, tilted to the drivers side Buick AND Cadillac - starter on passenger side, oil filter at front on passenger side

A-1. 4 bolt valve covers Buick small block family, integrated aluminum timing cover. Discrete exhaust runners.
215 - 3.500” x 2.800”, 1961-63
300 - 3.750” x 3.400”, 1964-67
340 - 3.750” x 3.850”, 1966-67

A-2. 4 bolt valve covers Cadillac big block family, integrated aluminum timing cover. Center exhaust runners are siamesed.
390 - 4.000” x 3.875”, 1963-63, short deck engine
429 - 4.125” x 4.000”, 1964-67, oversize 1963 390

B-1. 5 bolt valve covers - 2 bolts on top rail of valve cover, 3 on bottom Buick / Rover small block family, integrated aluminum timing cover. Factory installed in Oldsmobile applications ONLY.
1. Aluminum Block and Heads, test with magnet.
215 - 3.500” x 2.800”, 1961-63

B-2. 5 bolt valve covers - 3 bolts on top rail of valve cover, 2 on bottom Buick big block family, integrated aluminum timing cover, displacement stamped on top of the bellhousing
1. Ribs on valve covers are side to side, relief area in middle for displacement label
400 - 4.0400” x 3.900”, 1967-69
430 - 4.1875” x 3.900”, 1967-69
2. Ribs on valve covers are front to back, no relief area
455 - 4.3125” x 3.900”, 1970-76

C. 6 bolt valve covers Buick small block family, integrated aluminum timing cover
350 - 3.800” x 3.850”, 1968-81

D. 9 bolt valve covers Cadillac modern big block family, integrated aluminum timing cover, these are all variations of the 472.
368 - 3.800” x 4.060”, 1980-84
425 - 4.082” x 4.060”, 1977-79
472 - 4.300” x 4.060”, 1968-74
500 - 4.300” x 4.304”, 1970-76

II. Distributor at the rear of the engine (next to the firewall)

A. Buick Nailhead engine family, starter on driver side, oil filter at rear on passenger side. These are all variations of the 322.
264 - 3.625” x 3.200”, 1954-55
322 - 4.000” x 3.200”, 1953-56
364 - 4.125” x 3.390”, 1957-58
364 - 4.125” x 3.390”, 1959-61
401 - 4.188” x 3.640”, 1959-66
425 - 4.313” x 3.640”, 1963-66

B. Cadillac vintage OHV family, starter on passenger side, taller decks than the 63 and newer engines. Distributor and Oil pump at rear of block.
331 - 3.8125” x 3.625”, 1949-1955
365 - 4.000” x 3.625”, 1956-1958
390 - 4.000” x 3.875”, 1959-1962

B. Chevrolet - Distributor passes through the intake manifold. 4 bolt valve covers. Starter on passenger side. Oil filter at rear on drivers side.

D. Oldsmobile - Oil filler tube is at front of engine, feeds into timing cover. Distributor does NOT pass through the intake manifold. 10 bolt valve cover on almost all engines although some covers only have bolts in 5 positions. Valve cover is shaped liked a trapezoid with the top rail of the cover being longer than the bottom rail. Starter on driver’s side.
1. 14” between the heads at the base of the intake manifold - big block
2. 12” between the heads at the base of the intake manifold - small block

E. Pontiac - Intake separated from intake valley cover (also true of 49-64 Oldsmobile’s). Externally Pontiacs are the same, the distinction between ‘Big’ and ‘Small’ block is made on the basis of the Main Bearing diameter ( ‘Big’ = 3.250”, ‘Small’< = 3.000” ) 1. 1966 and earlier - 2 freeze plugs per side of block 2. 1967 and after - 3 freeze plugs per side of block

contributed by: bob k. mando