Overhead Cam
An overhead cam design was adopted by Pontiac in the 1966 model year. The block was based on the Chevrolet 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-cubic-inch (3.8 L) Chevrolet I6 block. The OHC head design put it in the avant-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.
Read more about this topic: Pontiac Straight-6 Engine
Famous quotes containing the words overhead and/or cam:
“There’s something wonderfully exciting about the quiet sing song of an aeroplane overhead with all the guns in creation lighting out at it, and searchlights feeling their way across the sky like antennae, and the earth shaking snort of the bombs and the whimper of shrapnel pieces when they come down to patter on the roof.”
—John Dos Passos (1896–1970)
“The youngest stood upon a stane,
The eldest cam and push’d her in.”
—Unknown. Binnorie; or, The Two Sisters (l. 15–16)