The MGA Twin Cam arrived in 1958 as the first dual-overhead-cam production MG.
MGA Twin Cam
The MGA Twin Cam was MG's much-anticipated, and valient, but ultimately unsuccessful, attempt at offering a more powerful version of the MGA. After so many years of old-fashioned MGs, the MGA of 1955 was like something from another world. And in one sense it was: an early product of British Motor Corporation’s brave new world of cost-conscious parts-bin engineering. Nevertheless, the A was an exciting, thoroughly competitive postwar MG sports car. Today it’s an honored classic.
The MGA served to introduce several components destined for many future BMC cars, notably a rugged new “B-Series” overhead-valve four-cylinder engine and associated four-speed gearbox. Features unique to the sports car included a massively strong new chassis, albeit with TD/TF-type independent front suspension. And -- finally -- there was an all-steel body with curvy, well-proportioned lines as modern as anything on the road.
Though tradition was served by the usual two-seat roadster, again with side curtains and an improved but still difficult top, a companion “bubbletop” coupe soon arrived with curved glass fore and aft, plus -- blimey! -- rollup door windows.
Early MGAs were 72-hp “1500s,” but 1959 introduced a 1.6-liter engine with 80 hp. Two years later, the 1600 became a Mark II with adoption of front disc brakes (drums continued aft) and more upright vertical grille bars. A stronger engine had always been planned, and it belatedly arrived in mid-1958 for special “1600 Twin Cam” models with standard all-disc brakes and center-lock alloy wheels.
Though cylinder size was unchanged from the ohv unit, the Twin Cam had its own alloy head with hemispherical combustion chambers and a high-for-the-day 9.9:1 compression ratio. These and assorted other tweaks added 28 hp, boosting top speed to at least 110 mph.
Performance was credible and the fun was back in the Twin Cam, although the car was plagued by poor engine reliability.
Unfortunately, the Twin Cam suffered serious knocking on ordinary fuel and, though a fierce performer when running right, it fast became known as a heavy oil-user. Add in a hefty $850 surcharge over comparable ohv models, and it’s little wonder that sales started poorly and got worse.
MG gave up in early 1960 at only 2111 examples, ironically just after curing the oil-burning and detonation problems. Leftover chassis were given pushrod engines and sold as “Deluxe” models. Of these, only 82 were “Mark I” roadsters and coupes; another 313 were Mark IIs. Overall, though, the MGA series was a resounding success, with some 101,000 built in seven years, more than double the number of T-Series MGs produced over two decades.