Pontiac straight-6 engine
Template:Lead too short Template:Infobox automobile engine The Pontiac straight-6 engine is a family of inline-six cylinder automobile engines produced by the Pontiac Division of General Motors Corporation in numerous versions beginning in 1926.
"Split Head" SixEdit
186Edit
In the 1920s Oakland Motor Car engineers designed an all new engine for their "companion" make, the Pontiac, that 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 was also used in GMC's 1927 T-10 and 1928 T-11 (their lightest trucks) as well as their next lightest truck, the T-19, beginning in 1928.<ref name=PW28>Template:Cite journal</ref> Development of the engine shared characteristics with the Oldsmobile Straight-6 engine, as GM worked together to develop the engine for Pontiac combined with the resources of GM-Northway Motor and Manufacturing Division.
This engine displaced Template:Convert with a bore and stroke of Template:Convert and was rated at Template:Convert at 2400 rpm when it was introduced. The compression ratio was 4.8:1.<ref name="concept">http://www.ConceptTemplate:Dead link Carz.com/vehicleTemplate:Citation needed</ref>
200Edit
In 1929, the "split head" Pontiac six was increased in displacement to Template:Convert. The horsepower rating increased to Template:Convert @ 3000 rpm. Compression was increased slightly to 4.9:1.<ref name="concept"/> 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. GMC also switched to the 200 cubic inch engine in 1929, using it into early in the 1933 model year.
Flathead SixEdit
208Edit
In 1935, Pontiac re-introduced their six-cylinder engine, as a Template:Convert 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 engine 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/GMCEdit
The 223 was a side-valve engine, and used a timing chain. The Template:Convert straight-6 was used in Pontiac automobiles (1937–40) and GMC trucks (1938 only).
239Edit
The Template:Convert straight-6 was similar in design to previous sixes. It was used from 1941 through 1954 only in Pontiac automobiles.
SpecificationsEdit
| Year | Model name (number) | Displacement | Output | Torque | Compression | Carburetor series (bbl) | |
| 1935 | Master & DeLuxe 6 (6-35) | Template:Convert | Template:Convert @ 3600 rpm |
Template:Convert @ 1600 rpm |
6.2:1 | Carter W-1 (1) | <ref name="Motor">Motor's Auto Repair Manual, Sixteenth Edition, Motor ,1953</ref> |
| 1936 | Master & DeLuxe 6 (6-36) | <ref name="Motor"/> | |||||
| 1937 | Six (6-37) | Template:Convert | Template:Convert @ 3520 rpm |
Template:Convert @ 1600 rpm |
<ref name="Motor"/> | ||
| 1938 | Six (6-38) | <ref name="Motor"/> | |||||
| 1939 | Quality & DeLuxe 6 (39-25) & (39-26) | Carter WA-1 (1) | <ref name="Motor"/> | ||||
| 1940 | Special & DeLuxe 6 (40-25) & (40-26) | Template:Convert @ 3520 rpm |
Template:Convert @ 1400 rpm |
6.5:1 | <ref name="Motor"/> | ||
| 1941 | Custom, DeLuxe & Streamliner Torpedo 6 (41-24), (41-25), & (41-26) | Template:Convert | Template:Convert @ 3200 rpm |
Template:Convert @ 1400 rpm |
<ref name="Motor"/> | ||
| 1942 | Torpedo & Streamliner Torpedo 6 (42-25) & (42-26) | <ref name="Motor"/> | |||||
| 1946 | Torpedo & Streamliner 6 (46-25) & (46-26) | Template:Convert @ 3400 rpm |
<ref name="Motor"/> | ||||
| 1947 | Torpedo & Streamliner 6 (47-25) & (47-26) | <ref name="Motor"/> | |||||
| 1948 | Torpedo & Streamliner 6 (48-25) & (48-26) | Template:Convert @ 1400 rpm |
<ref name="Motor"/> | ||||
| 1949 | Silver Streak 6 (49-25) | <ref name="Motor"/> | |||||
| 1950 | Silver Streak 6 (50-25) | Template:Convert @ 3400 rpm |
Template:Convert @ 1200 rpm |
<ref name="Motor"/> | |||
| 1951 | Silver Streak 6 (51-25) | Template:Convert @ 3400 rpm |
Template:Convert @ 1200 rpm |
<ref name="Motor"/> | |||
| 1952 | Silver Streak 6 (52-25) with manual trans. | Template:Convert @ 3400 rpm |
Template:Convert @ 1400 rpm |
6.8:1 | <ref name="Motor"/> | ||
| 1952 | Silver Streak 6 (52-25) with automatic trans. | Template:Convert @ 3400 rpm |
7.7:1 | <ref name="Motor"/> | |||
| 1953 | Chieftain 6 (53-25) with manual trans. | Template:Convert @ 3800 rpm |
Template:Convert @ 2000 rpm |
7.0:1 | Carter WCD (2) | <ref name="Motor"/> | |
| 1953 | Chieftain 6 (53-25) with automatic trans. | Template:Convert @ 3800 rpm |
7.7:1 | <ref name="Motor"/> | |||
| 1954 | Chieftain 6 (54-25) with manual trans. | Template:Convert @ 3800 rpm |
7.0:1 | <ref name="Motors">Motor's Auto Repair Manual, Motor,1963</ref> | |||
| 1954 | Chieftain 6 (54-25) with automatic trans. | Template:Convert @ 3800 rpm |
7.7:1 | <ref name="Motors"/> |
Overhead ValveEdit
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215Edit
A Template:Convert overhead valve straight-6 was produced in 1964 and 1965 but was not an original Pontiac design. Sometimes confused with the Buick designed and built [[Buick V8 engine#215|Template:Convert aluminum V8]] that Pontiac had used in the two years prior, the "Pontiac 215" was an adaptation of Chevrolet's 194 cu.in. inline 6 currently produced and the new Template:Convert overhead valve Turbo-Thrift straight-6. Quite different from Pontiac's previous straight-6s, it had a smaller bore Template:Convert than the Template:Convert larger Chevrolet engine and a Chevy bellhousing, but its flywheel/flexplate bolt pattern was Pontiac's.
Overhead camEdit
230Edit
A single overhead camshaft (SOHC) design was introduced by Pontiac in the 1966 model year as the standard engine in the Tempest. Offered also in 1967, the Template:Convert OHC 6 shared internal dimensions with the overhead valve Chevrolet straight-6 engine it was based on,Template:Citation needed but had unique cast iron block and head castings. Only the large cam carrier/valve cover was aluminum. It used a jackshaft (outside of the block) for oil pump and distributor drive. The jackshaft was driven by the fiberglass reinforced timing belt.<ref name="Spontiac">Template:Cite book</ref> It was offered with a single one barrel carburetor, rated at Template:Convert.<ref name="Spontiac">Template:Cite book</ref> A W53 Sprint version for the Firebird produced up to Template:Convert.
Considered advanced by Detroit engineering standards at the time, the Pontiac OHC 6 followed the Jeep Tornado I6 as the second post-World War II domestic-developed and mass-produced overhead cam automobile engine.<ref>Template:Cite journal</ref>
The Pontiac's single camshaft was supported by journals within the aluminum valve cover; no separate bearing shells were used. The cam was driven by a noise-reducing fiberglass-reinforced cogged rubber belt instead of the usual metal chain or gears. Valves were opened with finger followers (centered under the cam) that pivoted at one end on stationary hydraulic adjusters. The oil pump, distributor, and fuel pump were driven by an external jackshaft powered by a rubber timing belt nestled within an aluminum housing bolted to the right side of the block. The head had a single port face with both exhaust and intake valves on the left side and valve stems strongly tilted towards the left. This engine was used in the 1966-67 Tempest and Le Mans and 1967 Firebird.
An optional high-performance Sprint version featured high-compression pistons, hotter cam, dual valve springs, split/dual exhaust manifold, stronger coil, and the then new Rochester Quadrajet carburetor. rated at Template:Convert.<ref name="Spontiac">Template:Cite book</ref> Power was increased to Template:Convert in 1967.
Like other Pontiac engines of the era, the OHC 6 was not available in Canada with the exception of the Sprint version of the Firebird. Canadian-market Pontiac automobiles were equipped with the Chevrolet OHV six.
250Edit
The OHC Template:Convert was enlarged to Template:Convert for 1968 to 1969. The base engine produced Template:Convert while the 4 bbl Quadrajet Sprint versions were rated up to Template:Convert with automatic transmissions. The versions with a manual transmission received a hotter camshaft that boosted ratings to Template:Convert.
See alsoEdit
ReferencesEdit
External linksEdit
- [1] Pontiac Overhead Cam SIX Forum