Complete Stage II performance engines are available built to order for both the 1275cc and 1500cc. These offer a meaningful increase in power and torque while retaining everyday reliability.
For owners seeking a more tailored specification, bespoke engine builds can be discussed with the MGOC Spares sales team to suit specific competition or fast-road requirements.
Stage II Cylinder Heads
For owners carrying out a head rebuild without committing to a complete engine, Stage II cylinder heads are available as standalone items for both the 1275cc and 1500cc. These are gas-flowed and ported with reshaped combustion chambers and larger valve seats, delivering a worthwhile improvement in power and efficiency without compromising reliability for everyday road use.
Rear Oil Seal Conversion (A-Series)
The original 1275cc A-Series rear crankshaft seal is a scroll-type design that relies on a helical groove machined into the crankshaft to return oil to the sump. While effective when new, this seal type becomes progressively less effective as the crankshaft and scroll surfaces wear. A rear oil seal conversion kit replaces the scroll arrangement with a modern lip seal, providing a more positive and durable seal against oil leakage. This conversion is particularly recommended during any engine rebuild where the rear of the crankshaft is accessible.
The 1500 Triumph engine uses a lip seal in a separate housing from the factory, so the conversion is not applicable to the 1500.
Oil Cooler Kits
Oil cooler kits are available in three radiator sizes, ten-row, thirteen-row, and sixteen-row. The choice should consider the car's intended use: a ten-row unit is generally adequate for normal road driving, while thirteen or sixteen-row coolers suit sustained high-speed use or competition. Hose kits are model-specific, with separate kits for the 1275cc vertical-flow, 1275cc crossflow, 1500, and 1500 with integrated oil thermostat. Kits are available in both standard rubber and stainless steel braided options.
Oil Thermostat
An oil thermostat fitted in the cooler circuit prevents overcooling of the oil in cold conditions. Without one, the oil passes through the cooler continuously from cold start, which significantly extends warm-up time, and cold oil is too viscous for proper bearing lubrication. The thermostat diverts oil away from the cooler until the oil reaches approximately 80°C, at which point it opens to allow oil through the cooler.
Timing Chain Renewal
The 1275cc duplex timing chain and gear set should be renewed during any engine rebuild where the timing cover is removed, chain wear retards valve timing progressively and reduces engine performance. For the 1500, the single-row chain and tensioner should be inspected at each major service interval, as chain stretch on the 1500 is a known wear item that affects both performance and idle quality.