Pontiac Straight-6 engine
Encyclopedia
Like most American automobile
manufacturers, Pontiac
relied on the straight-6
design for their circa-World War II
automobiles.
This engine displaced 186.7 CID (3.25x3.75) and was rated at 40 bhp (29.4 kW) @ 2400 rpm when it was introduced. The compression ratio was 4.8-1.
The "split-head" six was discontinued by Pontiac at the end of the 1932 model year. Pontiac offered only eight cylinder engines during 1933 and 1934.
it also featured full-pressure oiling and insert type precision main and rod bearings. These two latter features greatly increased longevity and durability especially under high speed conditions.
, Pontiac shared their mainstream straight-6 engine with GMC
for truck use. It was also a side-valve engine, and used a timing chain.
The 223 CID straight-6 was used in Pontiac automobiles (1937–40) and GMC trucks (1938 only).
/pushrod engine design, quite different from the previous Pontiac straight-6 engines. It was a smaller bore (3.75") version of the 230 cubic inch Chevrolet inline 6.
Straight-6
, but had block and head castings unique to the OHC. Both head and block were cast iron; only the large cam carrier/valve cover was aluminum. The engine featured a Single Over Head Cam and was the base engine in the Pontiac Tempest
.
The Pontiac OHC-6 engine shared internal dimensions with the standard 230 CID Chevrolet I6 block. The OHC head design put it in the avante garde of Detroit engineering. The single camshaft was supported by journals within the aluminum valve cover; no separate bearing shells were used. The cam was driven by a glass fiber-reinforced cogged rubber belt, instead of the usual metal chain or gears, making it state of the art for the time, as well as very quiet. Valves were opened with finger followers (centered under the cam) that pivoted at one end on stationary hydraulic adjusters. The oil pump, distributor drive and fuel pump drive were not within the block, but were handled by an external jackshaft in an aluminum housing that bolted to the right side of the block. The jackshaft was driven by the rubber timing belt. The head had a single port face (exhaust and intake were both on the left side) and the valve stems were strongly tilted towards the left. This engine was used on the 1966 through 1969 Tempest and Le Mans
and the 1967 through 1969 Firebird
.
A high-performance version, called the Sprint, was an option. The Sprint featured high-compression pistons, a hotter cam, dual valve springs, a split/dual exhaust manifold, a better coil and utilized the then new Quadrajet
4-barrel carburetor. It was the first American high performance in-line six cylinder engine since the 1954 Chevrolet Corvette
.
The Pontiac OHC-6 engine ended production with the 1969 models.
Like other Pontiac engines of the era, it was not available in Canada
; Canadian Pontiac automobiles came with the Chevrolet OHV six instead.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
manufacturers, Pontiac
Pontiac
Pontiac was an automobile brand that was established in 1926 as a companion make for General Motors' Oakland. Quickly overtaking its parent in popularity, it supplanted the Oakland brand entirely by 1933 and, for most of its life, became a companion make for Chevrolet. Pontiac was sold in the...
relied on the straight-6
Straight-6
The straight-six engine or inline-six engine is a six-cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase...
design for their circa-World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
automobiles.
186
In the 1920s Oakland Motor Car engineers designed an all new engine for their "companion" make, the Pontiac, which was introduced in 1926. It was a side-valve design with a one piece cast iron block with three main bearings. An unusual feature was that it had two separate cylinder heads that each covered three cylinders. The Ignition distributor was mounted on top of the block in the gap between the heads.This engine displaced 186.7 CID (3.25x3.75) and was rated at 40 bhp (29.4 kW) @ 2400 rpm when it was introduced. The compression ratio was 4.8-1.
200
In 1929, the "split head" Pontiac six was increased in displacement to 200 CID. The horsepower rating increased to 60 bhp (44.2 kW) @ 3000 rpm. Compression was increased slightly to 4.9-1.The "split-head" six was discontinued by Pontiac at the end of the 1932 model year. Pontiac offered only eight cylinder engines during 1933 and 1934.
208
In 1935, Pontiac re-introduced their six cylinder engine, as a 208 CID straight-6. The 208 was produced in 1935 and 1936. It was a side-valve design with a timing chain, as was popular at the time. This engine featured a conventional one piece cylinder head, and the distributor was moved to the side of the block. The number of main bearings was increased to four. Like the Pontiac Straight-8 enginePontiac Straight-8 engine
The straight-8 was an eight-cylinder, in-line automobile engine that was used in production Pontiacs from 1933 to 1954. Introduced in the fall of 1932 for the 1933 models, it was Pontiac's most powerful engine at the time and was the least expensive eight-cylinder engine built by an American...
it also featured full-pressure oiling and insert type precision main and rod bearings. These two latter features greatly increased longevity and durability especially under high speed conditions.
223 Pontiac/GMC
Just as was done with their later V8sPontiac V8 engine
Pontiac began as a adjunct to the Oakland division of the General Motors line of automobiles in 1926. Pontiac successfully competed against more expensive 4-cylinder models with their inline flathead 6 engines. After outselling Oakland, Pontiac became the sole survivor of the two by 1932. In...
, Pontiac shared their mainstream straight-6 engine with GMC
GMC (General Motors division)
GMC is a manufacturer of trucks, vans, military vehicles, and SUVs marketed in North America and the Middle East by General Motors Company. In January 2007, GMC was GM's second-largest-selling North American vehicle division after Chevrolet, ahead of Pontiac....
for truck use. It was also a side-valve engine, and used a timing chain.
The 223 CID straight-6 was used in Pontiac automobiles (1937–40) and GMC trucks (1938 only).
239
The 239 CID straight-6 was similar in design to previous sixes. It was used from 1941 through 1954 only in Pontiac automobiles.Specifications
| Year | Model name (number) | Displacement cu in |
Output BHP (kW) @ RPM | Torque ft·lbf. (Nm) @ RPM | Compression | Carburetor series (bbl) | |
| 1935 | Master&DeLuxe 6 (6-35) | 208.0 | 80 (58.88) @3600 | 150(203.40) @ 1600 | 6.2-1 | Carter W-1 (1) | |
| 1936 | Master&DeLuxe 6 (6-36) | 208.0 | 80 (58.88 @ 3600 | 150 (203.40) @ 1600 | 6.2-1 | Carter W-1 (1) | |
| 1937 | Six (6-37) | 222.7 | 85 (62.56) @ 3520 | 161 (218.32) @ 1600 | 6.2-1 | Carter W-1 (1) | |
| 1938 | Six (6-38) | 222.7 | 85 (62.56) @ 3520 | 161 (218.32) @ 1600 | 6.2-1 | Carter W-1 (1) | |
| 1939 | Quality&DeLuxe 6 (39-25) & (39-26) | 222.7 | 85 (62.56) @ 3520 | 161 (218.32) @ 1600 | 6.2-1 | Carter WA-1 (1) | |
| 1940 | Special&DeLuxe 6 (40-25) & (40-26) | 222.7 | 87 (64.03) @ 3520 | 164 (222.38) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1941 | Custom,DeLuxe & Streamliner Torpedo 6 (41-24),(41-25),& (41-26) | 239.2 | 90 (73.59) @ 3200 | 175(237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1942 | Torpedo & Streamliner Torpedo 6 (42-25) & (42-26) | 239.2 | 90 (73.59) @ 3200 | 175 (237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1946 | Torpedo & Streamliner 6 (46-25) & (46-26) | 239.2 | 93 (68.45) @ 3400 | 175 (237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1947 | Torpedo & Streamliner 6 (47-25) & (47-26) | 239.2 | 93 (68.45) @ 3400 | 175 (237.30) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1948 | Torpedo & Streamliner 6 (48-25) & (48-26) | 239.2 | 93 (68.45) @ 3400 | 178 (241.37) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1949 | Silver Streak 6 (49-25) | 239.2 | 93 (68.45) @ 3400 | 178 (241.37) @ 1400 | 6.5-1 | Carter WA-1 (1) | |
| 1950 | Silver Streak 6 (50-25) | 239.2 | 90 (66.24) @ 3400 | 178 (241.37) @ 1200 | 6.5-1 | Carter WA-1 (1) | |
| 1951 | Silver Streak 6 (51-25) | 239.2 | 96 (70.65) @ 3400 | 191 (259.00) @ 1200 | 6.5-1 | Carter WA-1 (1) | |
| 1952 | Silver Streak 6 (52-25) with manual trans. | 239.2 | 100(73.59)@3400 | 189(256.28)@1400 | 6.8-1 | Carter WA-1 (1) | |
| 1952 | Silver Streak 6 (52-25) with automatic trans. | 239.2 | 102(75.07)@3400 | 189 (256.28)@1400 | 7.7-1 | Carter WA-1 (1) | |
| 1953 | Chieftain 6 (53-25) with manual trans. | 239.2 | 115(84.63)@3800 | 193(261.71)@2000 | 7.0-1 | Carter WCD (2) | |
| 1953 | Chieftain 6 (53-25) with automatic trans. | 239.2 | 118 (86.84@3800 | 193(261.71)@2000 | 7.7-1 | Carter WCD (2) | |
| 1954 | Chieftain 6 (54-25) with manual trans. | 239.2 | 115(84.63@3800 | 193(261.71)@2000 | 7.0-1 | Carter WCD(2) | |
| 1954 | Chieftain 6 (54-25) with automatic trans. | 239.2 | 118(86.84)@3800 | 193(261.71)@2000 | 7.7-1 | Carter WCD(2) | |
Overhead Valve
In the mid-1960s, Pontiac revived their straight-6 for a short time. Although it was of a different displacement, this Pontiac engine was based on Chevrolet's Generation 3 straight-6.Pushrod 215
The 215 CID straight-6 was produced in 1964 and 1965. It is sometimes confused with the 215 aluminum V8 used in the two years prior. It was an OHVOverhead valve
An overhead valve engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block , and uses pushrods or rods to actuate rocker arms above the cylinder...
/pushrod engine design, quite different from the previous Pontiac straight-6 engines. It was a smaller bore (3.75") version of the 230 cubic inch Chevrolet inline 6.
Overhead Cam (OHC-6)
The OHC-6 design was adopted by Pontiac in the 1966 model year. The block was based on the ChevroletChevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
Straight-6
Chevrolet Straight-6 engine
The Chevrolet inline 6 was Chevy's main engine from 1929 , through 1954, and was the base engine starting in 1955 when they added the small block V8 to the lineup. It had finally been completely phased out by 1990 in North America, but Brazil held on to their fuel-injected straight-6 through the...
, but had block and head castings unique to the OHC. Both head and block were cast iron; only the large cam carrier/valve cover was aluminum. The engine featured a Single Over Head Cam and was the base engine in the Pontiac Tempest
Pontiac Tempest
The Pontiac Tempest was an entry-level compact produced by the Pontiac Motor Division of General Motors, introduced in September 1960 for the 1961 model year....
.
The Pontiac OHC-6 engine shared internal dimensions with the standard 230 CID Chevrolet I6 block. The OHC head design put it in the avante garde of Detroit engineering. The single camshaft was supported by journals within the aluminum valve cover; no separate bearing shells were used. The cam was driven by a glass fiber-reinforced cogged rubber belt, instead of the usual metal chain or gears, making it state of the art for the time, as well as very quiet. Valves were opened with finger followers (centered under the cam) that pivoted at one end on stationary hydraulic adjusters. The oil pump, distributor drive and fuel pump drive were not within the block, but were handled by an external jackshaft in an aluminum housing that bolted to the right side of the block. The jackshaft was driven by the rubber timing belt. The head had a single port face (exhaust and intake were both on the left side) and the valve stems were strongly tilted towards the left. This engine was used on the 1966 through 1969 Tempest and Le Mans
Pontiac GTO
The Pontiac GTO is an automobile built by Pontiac Division of General Motors in the United States from 1964 to 1974, and by GM subsidiary Holden in Australia from 2004 to 2006. It is considered an innovative, and now classic muscle car of the 1960s and 1970s...
and the 1967 through 1969 Firebird
Pontiac Firebird
The Pontiac Firebird was built by the Pontiac division of General Motors between 1967 and 2002. The Firebird was introduced the same year as the automaker's platform-sharing model, the Chevrolet Camaro...
.
A high-performance version, called the Sprint, was an option. The Sprint featured high-compression pistons, a hotter cam, dual valve springs, a split/dual exhaust manifold, a better coil and utilized the then new Quadrajet
Quadrajet
In automobile mechanics, the Quadrajet is a four-barrel carburetor made by the Rochester Products Division of GM that was widely used in General Motors motor vehicles until 1990...
4-barrel carburetor. It was the first American high performance in-line six cylinder engine since the 1954 Chevrolet Corvette
Chevrolet Corvette
The Chevrolet Corvette is a sports car by the Chevrolet division of General Motors that has been produced in six generations. The first model, a convertible, was designed by Harley Earl and introduced at the GM Motorama in 1953 as a concept show car. Myron Scott is credited for naming the car after...
.
The Pontiac OHC-6 engine ended production with the 1969 models.
Like other Pontiac engines of the era, it was not available in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
; Canadian Pontiac automobiles came with the Chevrolet OHV six instead.