Visually Identifying GM V8 Engines of the 60’s and 70’s

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 carburetion 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

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

Bob, I was told by Buick engineers that the 401 and the 425 were cored differently. The 401 will NOT bore to 425 size.

hmmm, i guess i need to clarify that.

when i say 'x' motor is a bored or stroked version of 'y' motor i don't mean that the factory just stuffed a bigger hone in the hole, i mean that they're using the same bore centers and most of the rest of the original engine architecture. fer instance, you'll be able to swap heads between almost all of these engines.

i'll go back and modify the terminology on that.

in other news, 442.com has their FAQ wrong for the Caddy distributor. i just looked up the Cadillac engine that competed in the Popular Hot Rodding Engine Masters Challenge. the Caddy distro looks just like a Buick distro. i'll be editing that. now i think i might be on the track that Caddy valve covers have 9 bolts, can anybody verify that?
http://popularhotrodding.com/enginem...llenge08_z.jpg

gah.

what i wouldn't give for a WYSIWYG text editor on vBulletin.

70-71, 455 casting in the head has a year on end of the head side end in the year, the intake is a deep valleys on head/intake connection, note no EGR till 73 on back end, if opened the 70 71 have cast in the intake under neith. The 70 71 also have simple power steering pump bracket made of steel. In 72 Gm initiated the heat air pump idea. The intake has a heat rail for the air pump to connect to drivers side of intake, note here no EGR. In 72 the year "72" in cast in the head side end. 72 has a steel airpump bracket. 73 the intake has airpump heat tubes on sides of intake again as in 72 but note here the intake now has a EGR on back side of intake. The power steer and airpump bracket are steel. The year is cast in the head side ends as "73". The 74 is same as 73 but cast of "74" head now, and the bracket is now aluminum cast for power steer and airpump. This is also last year of real spring carb choke pulloff into intake, EGR and airtubes on the intake are still in use. In the 75-76 pollution years the intake is now gone with the air tubes as they tended to over heat the 455. thus a 75-76 have better intake for heat in a rebuild for normal driver. The cast of head numbers are now gone. The carb now uses a vaccuum heat tube into intake instead of spring and used a spring like old nail head had with a round cyl on side of carb and could be adjusted. All 455 were cast in the valley of the transmission at top back of the motors , The 455 is 2.5 inch longer front to rear of motor than buick 350 and has the same width as a 350 out side valvecover to outside valve cover is 29.5" The 75-76 Also used a vaccuum operated heat riser since the intake tubes are gone these pushed hot air back through the motor and did not get exhaust directly out but recurculated back in the motor to the other side. why? dont need the heat of exhaust back in the motor. The 74 is also the last available year for factory down pipe for dual exhaust with no catalytic converter, 75 on used a cat on all 455, the last 455 went off assembly line before Christmas shut down in 75 for the 76 year assembly line as all were 350 cars after holiday shutdown at Buick. The End of the decompressed 7.9-1 motor in 75-76. The internal did change for better in later years as oil and heat were delt more than early years of big Buick motors. Craig Minneapolis MN

I believe that the "Old Guy" is correct about the fact that 401s cannot be bored out to 425s. I heard it mentioned from a Buick guy many years ago.

In the Riv`s and Wildcats in 66 the nailheads were painted red and the only year to use the Q-JET intake--again Riv`s and Wildcats only.

401s in the GS Skylark were also red in 66, and all other 401s were green that year. All 425s were red in 66.

Doc, you are correct (DUH ME ) how could I forget about the Skylarks---I know CRS.............