1939 MG TB

The middle of April 1939, brought the end of the run of 3003 MG TAs. Following close on its heels was the new and improved MG TB. Even though the running gear was identical to the earlier model, there were several key elements to set it apart. A gearbox with much improved synchromesh and the now ubiquitous XPAG engine. This engine would continue under the bonnet of the T series right up to the TF. The XPAG was derived from the Morris Series M Ten engine.

The XPAG was to keep the same stroke, but the bore was increased to 66.5-mm, giving the ohv, four-cylinder engine a capacity of 1250-cc and a rating of 54 bhp. The new engine also benefitted from a much stronger bottom end and better valve timing, as well as a better designed cylinder head, a fully counterbalanced crankshaft and steel shell bearings for the main and big ends. As it was such a free-revving unit, it lent itself to a considerable level of tuning. This improved unit was mated to a dry-plate clutch and a transmission with better gear ratios from the previous MG.