The T-Series Twin Cams

by Kevin Clemens

      Most MG enthusiasts are aware that the Abingdon-on-Thames company produced a twin-cam version of the MGA in 1959 and 1960. But the Twin Cam MGA wasnt the first time that two camshafts were used to power a car carrying the MG octagon.

The Early Post-war Scene

      While specialized racing engines and virtually hand-built Duesenberg and Stutz models took advantage of the better breathing afforded by double overhead camshafts, very few production cars, particularly those made in America, had anything more sophisticated than side-valve engines through the end of the thirties and into the forties.

      In fact, overhead valves were considered quite advanced when they appeared on Oldsmobile's Rocket V-8 engine and Cadillac's V-8 of 1949 and William Lyon's remarkable double overhead cam six-cylinder Jaguar XK engine seemed radical when it was introduced in 1948. Ferrari joined the twin cam ranks in 1949 when Aurelio Lampredi converted Gioacchino Colombo's single cam V-12 Formula One engine, but it wouldn't be until the 1960s that a Ferrari GT car would be available to the public with a twin cam engine. The clever Jaguar engine was joined by another twin-cam six-cylinder engine in 1950 in the Aston Martin DB2. 1950 also saw the introduction of the new 1900cc four-cylinder from Alfa Romeo. Lightweight and powerful, the 1900cc engine formed the basis of Alfa powerplants for the next three decades. The 1300cc-twin cam came in 1954, followed by 1600cc, 1750cc and 2000 cc versions. These were high volume engines, yet were beautifully made and delightful to listen to, whether in a sedan or sports car.

Hot Rod Heaven

      About the time all of these exotic European twin-cam engines began to appear, American racers were beginning to find their MG TCs and TDs were no longer competitive against the early Porsches in the 1500-cc class. The MG racers were a resourceful lot, making their cars lighter by replacing flowing fenders with the cycle variety and cutting weight wherever they could. Engines were bored out and tuned for more horsepower, but the T-Series was coming near the end of its day in the competition sun. In an attempt to keep the cars more competitive, at least four individual efforts were made to create double overhead camshaft cylinder heads that would fit onto MG T-Series cylinder blocks. Because the hot rod movement was in full swing and because overhead cam cylinder heads had been created for Model A Ford engines and for twin-cam Offy racing engines, there was a fair amount of knowledge available about making up new cylinder heads. Each of these MG twin-cam T-series efforts was unrelated to the others as they were projects undertaken by well-to-do individuals who thought they could build a better mousetrap.

David V. Uihlein Special

The David V. Uihlein Special
      David Uihlein was a sports car enthusiast living in Wisconsin. At the age of 16 he landed a summer job in the Milwaukee shop of racing legends Carl and Tudy Marchese. Following his formal education and an apprenticeship at the family brewing business (Schlitz), Uihlein decided it was time to build an American sports car that could beat the Europeans. Working with the Marcheses, an Allis-Chalmers engineer named E.J. Healy, and famed race car constructor Weikko Leppanen, the project came together using largely MG TD components. The car itself looked like an Indy Roadster with fenders and the body was made from aluminum. The chassis was a heavily modified MG TD item.

The Uihlein XPAG twin cam engine
      The interesting part about the Uihlein special is its engine. The bottom end is an MG TD 1250-cc XPAG unit, chosen for its reliability and also because it was significantly less expensive than an Offy engine. On top of this block sits a hemispherical head with dual overhead camshafts. The head and cam housings are cast in nickel-alloy steel. The stock cam was left in the block to drive the oil pump and distributor while the two overhead camshafts are gear driven. Dual S.U. carburetors feed the fuel mixture to the intake ports on the left side while four ports lead to four straight pipes on the right side of the engine. The hemispherical head allows valves that are approximately 40 percent larger than original. Published reports of the time claimed the Uihlein engine would produce 90-bhp, significantly more than the 54-bhp of a standard XPAG engine, although the compression ratio was not reported. Don Marsh, a Columbus, Ohio racer who drove MGs in the early 1950s remembers seeing the bright purple Uihlein special at a race at Cumberland in the mid-fifties. We were pretty worried about it, with its special engine. But it wasnt very fast and we had no trouble beating it. Don was driving his lightweight Lester-MG that is now owned by Marv Primack in Chicago.

      David Uihleins intention was to offer a competition model built in Milwaukee to customers and to also provide the twin-cam head in kit form so that others could build their own twin-cam T-types. Neither plan came to fruition and today David Uihlein, a noted collector of classic cars and Miller Indy cars, still keeps his Uihlein Special in his private collection.

Runyan Twin Cam

The Runyan XPAG twin cam engine
      Dale Runyan was another man who dreamed of building a twin-cam engine kit that could be sold to MG owners. Working in the early 1950s with the legendary Bill Zimmerman, the pattern maker for Meyer-Drake-Offenhauser, and Norman Timbs (another famous West Coast race fabricator) a cast aluminum head was designed using a duplex roller chain to turn the overhead camshafts. The valves are closed with wire hairsprings similar to those used on the Norton Manx motorcycle and some early Ferrari models, instead of the more conventional coil springs. There is no provision made for valve lash adjustments. The cylinder head has a hemispherical combustion chambers with the spark plugs recessed into the head slightly, reportedly to allow for supercharging.

The Runyan head
      According to a Hot Rod magazine article written in March 1956, the Runyan head ran on an XPAG MG TD block on a dynamometer producing about 80 bhp at 5,000-rpm. Predictions were made that the engine would produce 110 bhp with larger carburetors at around 6500 rpm. According to Runyan, the price for a completed conversion kit would be around $500. Alas that was never to happen. The story is that the engine ran for about 20-minutes on the dyno before suffering a failure and was never run again.

The Runyan kit included extras
like a lightened flywheel
      Today the Runyan engine is owned by the Schulte family and is under the care of Carl Cederstrand in California. Louis Schulte had purchased the Runyan engine, patterns and drawings from Dale Runyan. In the 1980s he contacted Cederstrand, asking him to turn the remaining bits of the Runyan project into a running engine. Carl Cederstrand has spent a lot of time examining the admittedly beautiful castings and parts, but has decided that the design has some major problems. There is no way on the green earth of God that their DOHC conversion would have been a bolt-on as it is currently designed, said Cederstrand. It physically fits, sort of, in the engine compartment but after that, forget it.

      The Schulte family is interested in selling the entire Runyan engine and even Cederstrand admits that it could be made into a runner, given enough machine shop work. The Zimmerman patterns included with the Runyan engine are beautiful in both workmanship and materials. They belong in a museum, said Cederstrand.

Ken Miles?

      The only twin-cam T-series MG engine that has run with any degree of success is one currently owned by Don Martine in California. This engine has a murky past but may have been designed and built by Ken Miles for the use in RII, one of his West Coast MG specials in the mid-fifties. The engine surfaced in the late 1970s when Chris Nowlan, who worked at Moss Motors, owned it. The double overhead camshaft engine has an aluminum head that has been machined from a solid billet and with its engine-turned surface is described as looking like a Type 51 Bugatti. The head was mounted to a special MG TD racing block that had no holes in the deck for water passages into the head. Martine began his restoration of the unique engine in 1981, modifying it along the way allowing for things like adjustable valve clearances and designing manifolds for exhaust and intake using a pair of 1-3/4 S.U. carburetors. The twin overhead camshafts ride in five bearings and are driven with Offenhauser gears that are in turn driven by chain from an extra gear attached to the original camshaft. The combustion chambers are hemispherical with pre-ignition chambers, as seen on the Runyan engine. Martine finished the engine and installed it in a MG TC special in the mid-1980s. That special saw lots of action until it was involved in an accident and at last report was still being rebuilt in California.

Puma Engine

      Even more obscure than the engine owned by Don Martine is the Puma engine. Lawrie Alexander, the former sales manager at Moss Motors, discovered this engine in the early 1980s. The engine dates from sometime in the early 1950s. Alexander got the engine running and installed it in an MG TD. He even drove it to an MG meet in Canada from Santa Barbara before the cast cylinder head cracked. This engine then passed to Chris Nowlan, making him the only person who has ever owned two of the twin-cam MG TD engines. Nowlan was unable to get the cracked head repaired and eventually sold the engine to an MG enthusiast in England. At last report the cracks have been repaired and the engine is running once again.

The Factory Does it

      After the Second World War, MG had returned to record braking, primarily using pushrod versions of its production engines. However, in 1956 EX179 was fitted with a twin-overhead camshaft supercharged engine and took sixteen Class F awards. In 1957, the company was back at the Utah salt flats with EX181, this time powered by a prototype of the MGA Twin Cam engine fitted with a Shorrock supercharger. Stirling Moss captured five Class F records with speeds as high as 245.6 mph. Two years later, with the engine bored out and even more highly tuned, Phil Hill broke six Class E records in EX181 with a top speed of 254.9 mph.

      With the introduction of the MGA and subsequently the MGA Twin Cam, all interest in designing and building hot rod T-type twin cam engines disappeared and the four attempts became little more than a minor footnote in MG lore. What is perhaps most interesting is that the factory-built MGA Twin Cam suffered some of the same problems as these early pioneers did in their previous twin-cam efforts. Ultimately, even MG gave up on the idea of a highly tuned twin-cam engine and simply increased engine capacity to gain what they needed in performance. Still, given that none of the twin-cam XPAG designs were a rousing success, it is amazing that even after almost fifty years, each of these MG oddities still exists and that all of the four have the potential to someday run again.