The next GM car to offer a belt-driven overhead camshaft was the Chevrolet Vega, which debuted in 1971. It spawned a Pontiac version, the Astre, in 1975, although Pontiac didn’t use the Vega’s 140 cu. in. (2,286 cc) OHC engine for long. In 1978, the Vega four was replaced by the 151 cu. in. (2,471 cc) pushrod “Iron Duke” engine, which Pontiac used well into the eighties.
By the late seventies, belt-driven overhead cams were becoming very popular, particularly on inexpensive four-cylinder engines. Sadly, many later timing belts were far less robust than Pontiac’s was and some OHC engines had an alarming tendency to eat valves if the belt snapped. By the beginning of the 21st century, concerns over belt longevity — and the high cost of changing a timing belt on a modern transverse engine — prompted a move back to timing chains. Timing belts are now becoming rare; even Honda has adopted chain drive for its more recent engines.
Hydraulic valve adjusters were slower to spread to other mass-market cars, although they began appearing on some luxury cars in the early seventies. They are now extremely common on OHC engines, in part because maintaining a constant valve lash helps to control exhaust emissions. (Having owned several cars that required valve adjustments every 15,000 miles (24,000 km), however, the author also considers hydraulic lash adjusters a tremendous convenience.)
It’s unfortunate that the Pontiac OHC six became something of a dead end. The Sprint, in particular, offered a combination of decent power, modest weight, and respectable fuel economy that was not seen again on an American car for years afterward. Along with the turbocharged Oldsmobile Jetfire V8 of a few years earlier, it was one of the most sophisticated American engines of its era. It had its faults, but none of them was crippling and most can be rectified today with a competent rebuild and regular oil changes.
The stillborn OHC V8s are even more tantalizing. Even if they had made to production, it would probably have been on a very limited basis, like the earlier Super Duty engines, but if DeLorean and McKellar had had their way, they might well have spawned mass-production derivatives, if only for homologation purposes. It’s easy to understand why the prospect of bolt-on OHC heads for the GTO had buff book editors salivating.
Alas, it was not to be. Only one of the engines made it to the street, a SOHC 421 that Mac McKellar received as a parting gift on his retirement in 1982. Installed in McKellar’s 1963 Grand Prix, it was a fearsome sleeper, a sad — and potent — reminder of what might have been.
# # #
A little over a year after this article was written, we learned of the death of Malcolm McKellar, who passed away on April 8, 2011. He was 90 years old. McKellar outlived his former boss, John DeLorean, by six years: DeLorean died in 2005 at the age of 80.
NOTES ON SOURCES
Our sources on the development of the “Cammer” included Jim Black, “Buyer’s Guide: 1966-’67 Pontiac Le Mans Sprint,” Hemmings Muscle Machines June 2009, and “Pontiac’s Fantastic Six,” (n.d., The Pontiac-Oakland Club Overhead Cammers Chapter website, www.overheadcammerschapter. 150m. com, accessed 10 April 2010); Marc Cranswick, Pontiac Firebird – The Auto-Biography (Car & Motorcycle Marque/Model) (Poundbury, Dorchester: Veloce Publishing, 2003); John DeLorean and J. Patrick Wright, On a Clear Day You Can See General Motors: John Z. DeLorean’s Look Inside the Automotive Giant (Chicago, IL: Avon Books, 1979); John Ethridge, “Tempest’s New Cammer!” Motor Trend Vol. 17, No. 9 (September 1965), pp. 40-44; Kit Foster, “1967 Pontiac Firebird Sprint: OHC from John Z’s PMD,” Special Interest Autos #150 (November-December 1995), reprinted in The Hemmings Motor News Book of Pontiacs: driveReports from Hemmings Special Interest Autos, ed. Terry Ehrich (Bennington, VT: Hemmings Motor News, 2001), pp. 118-127; Wick Humble, “1961 Pontiac Tempest: But cars aren’t supposed to have curved driveshafts,” Special Interest Autos #48 (November-December 1978), reprinted in The Hemmings Motor News Book of Pontiacs , pp. 78-86; Jeff Koch, “John Z. DeLorean: Thoughts and memories from the immortal creator of the GTO, 30 years later,” High Performance Pontiac February 1994, pp. 22-23; George Mattar, “1966 Progressive Pontiac: PMD’s advanced overhead-cam-six Tempest for 1966,” Hemmings Classic Car April 2005; Mike Mueller, “When Less Was More: Pontiac Overhead-Cam Six-Cylinder,” American Horsepower: 100 Years of Great Car Engines (St. Paul, MN: MBI Publishing Company, 2006), pp. 117-121; Eric Nielssen, “Pontiac’s New SOHC Six,” Car and Driver September 1965, reprinted in Car and Driver on Pontiac 1961-75 (Brooklands Road Tests), ed. R.M. Clarke (Cobham, Surrey: Brooklands Books Ltd., 1986), pp. 36-38, 59; Jan P. Norbye, “Sensational New OHC Six from Pontiac,” Popular Science Vol. 187, No. 2 (August 1965), pp. 37-41; and Jan P. Norbye and Jim Dunne, Pontiac 1946-1978: The Classic Postwar Years (Osceola, WI: Motorbooks International Publishers & Wholesalers, 1979).
Additional technical details came from Doc Frohmader, “Pontiac OHC” (2006, Webrodder.com, www.webrodder. com, accessed 14 April 2010) and Donald J. Hoffman, 1966, “Hydraulic Lash Adjuster,” U.S. Patent No. 3,273,548, filed 29 September 1965 and issued 20 September 1966.
Information on Pontiac’s other OHC engines came from Eric Dahlquist, “Big Medicine from Pontiac,” Hot Rod March 1968, pp. 30-35; Don Keefe, “Dept. X: Malcolm ‘Mac’ McKellar’s 1963 Grand Prix is powered by the world’s only surviving OHC 421 Pontiac V8!” High Performance Pontiac October 1990, pp. 30-31; Rocky Rotella, “Pontiac V8 Engines – Photographing Legends,” High Performance Pontiac March 2010, www.highperformancepontiac. com, accessed 10 April 2010; and Bob Wicker, “An Interview with Herb Adams” (January 2010, Pontiacs Online, www.pontiacsonline. com, accessed 10 April 2010).
Additional background information on other American OHC engines came from Ray T. Bohacz, “Mechanical Marvels: Only in a Jeep: The 1962 Willys Overhead Camshaft 6-cylinder Engine,” Special Interest Autos #187 (January-February 2002), pp. 54–56; “Evolution of the Wills St. Claire” (2008, Wills Ste. Claire Museum, www.willsautomuseum. org, accessed 11 April 2010); Pat Foster, “The Other Overhead-Cam Six,” Special Interest Autos #150 (November-December 1995), reprinted in The Hemmings Motor News Book of Pontiacs, p. 123; Roger Huntington, “Will Camshafts be Kicked Upstairs? Progress Report on Overhead Cam Development, Yesterday, Today or Tomorrow?” Motor Trend Vol. 16, No. 7 (July 1964), pp. 56-57, 90-92; and John R. Bond, “Willys 4wd Wagoneer,” Car Life Vol. 10, No. 3 (April 1963), pp. 54–61.
Some information on the Red Baron came from Moldy Marvin, “The Tom Daniel Story” (2004, Ratfink.org, www.ratfink. org, accessed 11 April 2010).
We also consulted the following period road tests: Jim Dunne, “’66 Tempest: A tiger in performance, a dog on gas,” Popular Mechanics Vol. 125, No. 5 (May 1966), pp. 82-84, 230; John Ethridge, “OHC in a Tempest,” Motor Trend Vol. 18, No. 1 (January 1966), pp. 46-49; John Ethridge, “Sporty Specialties: Cougar & Firebird,” Motor Trend Vol. 19, No. 5 (May 1967), pp. 34-37, 41-42; Jan P. Norbye, “How Hot Can a Six Get?” Popular Science Vol. 188, No. 6 (June 1966), pp. 70-73; “Pontiac Tempest Sprint,” Car and Driver December 1965, and “Pontiac Le Mans Sprint,” Car and Driver February 1967, reprinted in Car and Driver on Pontiac 1961-75 (Brooklands Road Tests); “Pontiac Tempest Sprint & GTO: It’s Still….Six for the Money and Eight to Go!” Car Life May 1966, reprinted in GTO Muscle Portfolio 1964-74 (Muscle Portfolio Series), ed. R.M. Clarke (Cobham, Surrey: Brooklands Books Ltd., 1998); “A Brace of Birds: The Sprint and the 400 from among Pontiac’s Five Firebirds,” Car Life August 1967, John Ethridge, “Fire Breathing Bird…first of the spring from Pontiac,” Motor Trend Vol 19, No. 3 (March 1967); “Firebird Sprint: The Sensible Supercar,” Cars December 1967; Steve Kelly, “How Do You Say ‘PFST’?” Motor Trend Vol. 19, No. 7 (July 1967); “Look What They’re Doing to the Firebird Now,” Car Life April 1968; Jon McKibben, “Fitch Firebirds: With the Corvair market diminishing, John Fitch finds another car to improve,” Road & Track April 1968; and “Pontiac Firebird Sprint,” Road & Track June 1967, all of which are reprinted in Firebird and Trans-Am Muscle Portfolio, 1967-1972, ed. R.M. Clarke(Cobham, Surrey: Brooklands Books, Ltd., 1998).
We later updated the article to note the passing of Malcolm McKellar, based on information from Richard Lentinello, “RIP, Mac McKellar,” Hemmings Daily, 2 May 2011, blog.hemmings. com, accessed 15 June 2011; and Paul Stenquist, “Malcolm McKellar, Pioneer of the Pontiac Overhead-Cam Engine,” New York Times 3 May 2011, wheels.blogs.nytimes. com, accessed 15 June 2011. We confirmed McKellar and DeLorean’s dates of birth and death via the Social Security Death Index.
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