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GM Legend "Mac" McKellar

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by John Gunnell  More from Author

Big Mac Made Pontiacs Go

Photos by the author and courtesy of GM.


If you are into 1950s-1960s Pontiac performance engineering, the name McKellar is probably familiar to you. Malcolm R. “Mac” McKellar spent over 40 years of his life – between 1941 and 1982 – working as a staff motor engineer for Pontiac Motor Division. During this period, he helped develop high performance V-8s and two unique Tempest series engines. The Tempest powerplants were called the “Indy Four” and the overhead cam “Sprint Six.”

When Pontiac started in 1926, its first chief engineer, Ben Anibal, was known as an engine wizard and set a tradition for the company’s engineers to follow. However, his 1947 successor, George Delaney, wasn’t an engine specialist. When market pressures forced Pontiac to start developing its first postwar V-8 engine, Delaney called on Mark Frank, a staff engineer on engines, to supervise the project and uphold the tradition.

Frank had two assistants who worked closely with him: Clayton B. Leach and Edmund L. Windeler. Leach held an A. B. degree in mathematics from Park College and then attended the GM Institute from 1935 to 1937. He joined Pontiac in 1937, the same year Mac McKellar came aboard GM. Windeler earned his B.S. degree in mechanical engineering from Virginia Polytechnical Institute in 1936, the same year he joined Pontiac as an engineering test driver. He was appointed supervisor of the company’s Power Development Section in 1945.

Mac’s father – Charles McKellar – worked for General Motors as a foreman at the GM Proving Ground in Milford. His son got to see some of the cars he brought home and must have been impressed by the Pontiacs, as he bought a used 1937 Pontiac as his first car. It cost the princely sum of $300. After finishing high school, Mac became a student at the GM Institute, and he landed a job in the engine design department in 1941. During World War II he was drafted into the army, but he returned to his Pontiac job after a 22-month military stint.

In the early postwar years, Pontiac stuck with L-head sixes and eights longer than everyone else except Packard. However, with the success of the Cadillac, Oldsmobile and Buick V-8s, the in-line engines were hurting Pontiac sales. The company was interested in developing a V-8 engine, and Mac was the man to do it. McKellar once told the author that the original plan was to have him design an L-head V-8, since that type of engine had fewer parts and was simpler and cheaper to make. Fortunately, experimental flathead engines didn’t breathe as well as overhead valve V-8s, so overhead valves got the final nod at Pontiac.

The late John Sawruk, Pontiac’s official historian, used to publish hidden facts about the cars, and one of his favorite hidden facts was that the 1953 Pontiac frame has holes in it for mounting a V-8 engine. Mac McKellar confirmed that there were plans to use the V-8 in 1953, when he spoke to Jan Norbye and Jim Dunne for their book Pontiac The Postwar Years.  “It was postponed partly because of design and production problems, and partly for economic reasons,” he told the two writers. “We could have had it out sooner, but the feeling was that we had to produce an engine that was economical to build and try to be competitive on price in our segment of the market, as it was envisioned at that time.”

Mark Frank had McKellar design an engine using a wide bore and a short stroke, which was the format GM divisions seemed to prefer in the ’50s. According to a presentation called “New Pontiac V-8 Engine” that Leach and Windeler made at the SAE Golden Anniversary Meeting in Detroit on Jan. 12, 1955, McKellar had four main objectives in his engine design: (1) Outstanding performance with assured adaptability to future fuels; (2) Proved durability, equaling or exceeding its predecessor (the Pontiac L-head straight eight) in all respects; (3) Ready adaptability to displacement increases without major tooling changes and with no compromise to engineering function; and (4) Overall simplicity of design for complete ease of manufacturing and convenient servicing.

The original 287-cid Pontiac V-8 was offered in 173-, 180-, and 200-hp options. In 1956, it became the 317 V-8 with up to 227 hp. The basic 1957 Pontiac V-8 was the 347, but a new 370 fuel-injected V-8 was used in the ’57 Bonneville convertible. The 370 was then used in all 1958 models and, in 1959, it became the legendary 389, which came in a bunch of “flavors” up to Tri-Power.

By 1959, Elliott M. “Pete” Estes had taken over as head of Pontiac Engineering. He reorganized the section, making Mark Garlick executive engineer. H.R. Field was a chassis engineer and John P. Charles held the title assistant chief engineer in charge of testing and reporting. On the engine side, Ed Windeler was design supervisor, and Clayton B. Leach and Mac McKellar were design engineers. John DeLorean was in charge of advanced engineering.

McKellar’s aforementioned “Indy Four” was made around this time by cutting the 1959 Pontiac 389-cid engine in half. In fact, in one early test, McKellar simply put large holes in a 389 V-8’s four left-bank pistons and disconnected the valvetrain parts for those cylinders. Even after those changes, the big Pontiac that the altered engine was in could hit 92 mph and register decent gas mileage.

Norbye and Dunne documented some of the struggles McKellar encountered in getting test versions of the four-cylinder engine balanced. He must have done okay with the job, since the car got good reviews in Motor Trend and Pontiac sold enough Tempests to move the division into third in total auto industry sales. It was the best Pontiac had ever done, and hopefully Mac McKellar got a raise.

Raise or not, McKellar grew quite famous among racing fans and muscle car lovers for his design of 12 special and exotic racing camshafts that went into Pontiac’s factory-built racing engines. With his help, the big Pontiac Catalinas finished 1-2-3 in the 1961 Daytona 500, setting a new record for the race with a winning average of 149.601 mph.

Each of these cams was well-known to enthusiasts by the designer’s name and the number that followed. For example, the McKellar No. 6 cam, of 1961, was a fairly mild type with standard lift, but the intake valve duration was extended to 283 degrees and exhaust valve duration was 293 degrees.

The McKellar No. 7 cam, released the same year, was a bit wilder. It had a 0.414-inch lift, 301 degrees intake duration, and 313 degrees exhaust duration. It was known as a more temperamental design, but drag racers were concerned as much about driving a high-strung automobile as they were about going fast. And Mac knew how to make Pontiac engines go fast. 

The “King of the Drag Strip” for ’61 was the McKellar No. 10 cam designed for applications with solid valve lifters. It offered a 0.520-inch lift and 306/320 intake/exhaust valve duration. Later, the cam profiles of the No. 10 were modified for use in combination with hydraulic valve lifters.

McKellar-cammed cars tore up quarter-mile strips all across America, as well as a good number of circle tracks. During 1962, J.L. Meador campaigned a Super Duty Catalina hardtop sponsored by Van Winkle Pontiac of Dallas, Texas. This “Poncho” was equipped with a 421-cid, 373-hp firebreather with dual NASCAR type quad carburetors and a McKellar No. 11 camshaft. Clocking 105.75 mph and a 13.59-second elapsed time, the Waggoner-Meador-Van Winkle Pontiac tore up stock competition in no uncertain manner. Fireball Roberts took the Daytona 500 with a McKellar No. 11 cam under his hood.

Since the Indy Four lacked the power desired for the larger Tempest coming out in 1964, Mac McKellar began work on a new in-line six. He designed an advanced overhead cam six, but GM didn’t allow enough time to fully develop and test the engine. The 1964-1965 Tempest did offer a six, but it was basically a Chevrolet overhead valve engine assembled in Pontiac factories. It was not an exciting engine, but Mac did get to hot-rod the 389 for the 1964 GTO.

John Z. DeLorean was a big fan of exotic imported cars, and the original design for a Pontiac overhead cam six was sparked by his advanced design group. The design was then given to McKellar for further development and production design work. McKellar knew that eliminating pushrods and rocker arms would give him more ponies at high rpm, with adequate torque throughout the speed range and smooth idle characteristics.

The overhead cam six was so exciting and so well-received that Pontiac had Mac develop some experimental overhead cam V-8s, too. “Exclusive: Pontiac’s overhead cam V-8s,” said a headline above the banner of the March 1968 edition of Hot Rod magazine. “Pontiac’s McKellar reveals why OHC V-8s may soon be production engines,” read a cover blurb next to a picture of Mac behind a very exotic-looking powerplant.

McKellar also helped create later Pontiac performance mills, including HOs, Ram Airs and the Super-Duty 455 for 1973-1974 Formulas and Trans Ams. As Pontiac chief engineer Jay Wetzel noted in 1982, “Mac was the engine architect who led us through Wide-Track, GTO, Tri-Power, 400, 421, 455 and Super Duty, followed with 301 and 155 (2.5L) engines.”

When Mac McKellar retired from Pontiac on June 25, 1982, over 160 Pontiac executives, engineers, production experts and supplier reps appeared at his retirement party. Guests in attendance included such people as Jay Wetzel, Bob Newill, Russell Gee, Skip McCully, Steve Malone, Dimitrie Toth, Mike Hicks and your author.

Jay Wetzel, who was Pontiac’s chief engineer between September 1982 and June 1984, presented Mac with a certificate. It started with the wording, “Pontiac Motor Division of General Motors hereby decrees the honorary title of Doctorate of Engines Emeritus be conferred on Malcolm R. McKellar in recognition of his proficiency in the engineering of automotive powertrain systems.”

George Tozar also read letters of appreciation from Clayton Leach, and two former Pontiac general managers that McKellar had worked under, Estes and DeLorean. Bob Dorn, who was Pontiac chief engineer then, said, “Those who have been touched by Mac during their professional careers are very lucky.”

At the close of ceremonies, Mac took the podium and announced that he planned to spend his newfound leisure time in the restoration of a 1962 Grand Prix, and a year later, a Pontiac Bonneville with the 421 HO V-8. “As you can tell,” he said, “Old hot rodders never die; their top speed just declines a little.”






In the early ’60s, “Mac” McKellar was turning out hot cams and other engine goodies for cars like this ’62 Catalina convertible. His engine designs helped Pontiac get a firm hold on third place in industry sales.




Here is McKellar’s ’63 Bonneville convertible near Detroit’s Fisher Theatre. Mac also owned a ’62 Grand Prix and one of the experimental Pontiac overhead camshaft V-8s.



Pontiac brass snuck the GTO out under GM’s nose by making the 389-cid V-8 part of an option. The 389 they used in the first real muscle car had been tweaked by none other than McKellar.



In 1983, Pontiac Motor Division Product Engineering published a 75th Anniversary hardcover that included this page recognizing Malcolm R. “Mac” McKellar as the “Mastermind of the GTO V-8 engine.”



The concept of a Pontiac overhead cam six came out of the Pontiac advanced engineering section run by DeLorean (shown), but it was McKellar who got the job of drawing up the actual production version.




McKellar played a big role in engineering the original 1967 Firebird, a car that was offered with both his overhead cam six and his Ram Air V-8. Mac always said he enjoyed working for Pontiac during the division’s performance years.


Informal invitations to a June 25, 1982 retirement party for Mac McKellar carried a great cartoon of the legendary engine expert.



“Pontiac Motor Division of General Motors hereby decrees the honorary title of Doctorate of Engines Emeritus be conferred on Malcolm R. McKellar in recognition of his proficiency in the engineering of automotive powertrain systems,” says the certificate Jay Wetzel is presenting to Mac.


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