Morris Car Engines – Used Cowley engine, Isis, Mini Minor

Published by Carl Wilson on

The Morris Motor Company, a British car engines manufacturing company. After the incorporation of the company into larger corporations, the Morris name remained in use as a marque until 1984. Morris produced an amazing car engine which are readily available as used, reconditioned or secondhand today.

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Morris from the Anzani Engine Factory

had been given the task of improving a rather poor update of a Morris sidevalve new engines. This update had been converting a 1292cc 10hp Morris sidevalve into an overhead valve unit. The ‘MPJM’ ohv engine was fitted to the Series 3 Morris Ten/4, and only used for one year. A virtually identical ‘MPJW’ engine had been fitted to the 1936 Wolseley Ten/40, and the MG ‘TA’ Midget as the ‘MPJG’, again both of 1292cc. Claude was to take this Morris engine, and without too much fuss improve it in detail, to be fitted to the new chassisless Morris 10hp saloon, the ‘M’ Series.

The MPJM/MPJG series engine

had prooved to not be of the best, as it still used details dating back to the early Morris Bull Nose cars, mainly in its 102mm stroke. Like many companies Morris had tried a short-cut to ohv engines, by simply modifying an existing side-valve unit. Claude was given the task of sorting this all out. He reduced the stroke to 90mm, and Morris employees then dubbed the engine the ‘ Short-stroke Morris Ten ‘M’ Engine’.

This was because the 1140cc ”XPJM’ engine went into the new monocoque 10hp car, the 1939 Morris Ten Series ‘M’. The 90mm stroke was not new to Morris, it was in use in the current 918cc Morris Eight and 1378cc Morris Ten/Six, both side valve engines. Claude had strengthend the internals, improved the ports and the breathing, and had quietly produced the foundation of an engine that would become world famous later. The 1140cc engine naturally also found itself in the 1939 Wolseley Ten/40 Series 3 version of the Morris Ten Series ‘M’.

Morris Motors named the engines from this range the ‘X’ series, and they were to last from 1938 through to 1956. After designing Anzani and Morris engines, Claude went on to be involved in another ‘X’ series of engines, as after the war he helped design and develop Jaguars ‘XK’ six cylinder masterpiece. He worked for William Lyons along with great names like William Heynes and Walter Hassan. Claude was very involved in the now famous Jaguar V12 engine at Browns Lane, as chief designer for the company eventually, so his experience on the little XPAG prooved very useful to the UK motor industry.

The Morris ‘X’ series of engines was indeed becoming a success. MG had tried the Morris 10/4 Series 2 converted 1292cc side-valve engine in the 1936 MG TA Midget, having been forced to do so by the new management, now that their free-reign had been drastically shortened. When the 1140cc XPJM engine was seen by MG, they saw it obviously had development potential.

The engine was stiffened up more, connecting rods and big ends strengthened, stronger pistons, cylinders bored out to give 1250cc, and given bigger valves and ports. This went into an updated TA to be called the 1938 TB Midget. A long association of the XPAG engine as it was named with MG had begun.

A modified Morris Series Ten ‘M’ gearbox with remote gearchange added was part of the mechanical package, and together the engine and gearbox produced a very pleasant and driveable sports car. One of the attractions of the XPAG engine was its ability to rev freely, and its excellent bhp/torque figures for its size.

MG were more than pleased with the XPAG engine, and it was only WW2 that stopped the TB roaring away to more success, and the introduction of a MG Ten/4 six light saloon. This saloon was later called the ‘YA’, ( after the YB’s introduction,) which used a single SU carburetter version of the TB unit, and a gearbox without the remote gear change.

This coincided with the start of the climb to success of our little 1140cc and 1250cc ‘X’ series engine. In the post-war Morris ten Series ‘M’ and the Wolseley Ten/40, ( same car, differing grill, badging and interiors,) the 1140cc unit was pouring out of Morris Motors by the thousands.

The engine had not really been out of production, as it was being made all through the hostilities as a utility unit fitted to power water pumps, petrol/electric sets, hydraulic pumps, and the like for the armed services, ( named the 1939-45 MPJM/U.) Oddly, Morris went back to its side-valve engine in the car that replaced the Series ‘M’ Ten, as the 1948 ‘MO’ Oxford. The Wolseley 4/50 used the same body and chassis, ( again, ) but with a four cylinder single ohc engine. Wolseley’s had always been up-market Morris’s since Bill Morris had brought Wolseley Motors back in 1927 for their excellent engines.

The ‘X’ series was getting good press reviews in the motoring world. In Morris, Wolseley and MG form it was renowned for its quiet running and freedom from vibration, both products of a properly counterbalanced forged crankshaft with accurately fitting replaceable shell bearings, and good breathing.

The ability to rev freely was noticed as well, as this was one of the first ‘modern’ high-revving engine fitted to a family car. In the 1938 Morris Ten Series ‘M’ the 1140cc ‘X’ series engine propelled the car to a maximum speed of 66mph. In the 1947 MG YA the 1250cc version propelled this larger saloon to 69mph. In both saloons only a single SU carburetter was used. Fitted with twin SU’s into the 1945 MG TC top speed was recorded as 77mph.

The 1952 Wolseley 4/44 made 70mph mainly because of its good air-flowing shape, and the 1953 1466cc MG TF 1500 reached 85mph, which is not bad when you consider all the ‘T’ types have the coefficient of drag ( CD,) of a brick! Today we consider the XPAG to be a very ‘tappety’ engine when compared to modern and silent ohc engines, that sound more like hair-dryers than cars.

The 1250cc ‘XPAG’ version of the small but lively Morris engine was also in huge demand. In the MG it had been improved further with a timing chain tensioner soon after being fitted into the TB. The 1938 ‘TB’ had become the ‘TC’ Midget in 1945 with a few chassis modifications. By 1949 some ten thousand XPAG engines had been fitted to TC Midgets, by 1952 another 6,158 to the YA saloon, 877 to the YT tourer, and by 1953 another 1,301 to the YB saloon.

The MG model that really used the XPAG, and the one for which many remember it, is the immortal TD Midget. Between 1949 and 1953 28,643 XPAG fitted TD’s were sold, and add to that another 1,022 TD Mk2 Midgets. The XPAG MG engine was in its hey-day. It was being tuned to terrific power levels of over 100bhp per litre with superchargers in motor-racing. Specialist car makers liked the engine, and the XPAG found its way onto many racing tracks. The high speed runs of Goldie Gardner in September 1951 for USA class ‘F’ cars in EX135 no doubt helped the image of the engine. Producing 92bhp normally, fitted with a supercharger it could be boosted to 210bhp at 7,000rpm for short periods, then the little 1250cc engine managed 139.3mph.

The smaller Morris and Wolseley 1140cc engines had been built in large numbers, totalling some 90,000 cars. The engine was modified as it went along in production, and in MG form seems to be in three separate series. The Wolseley 4/44, was looking like a high built MG Magnette ZA with a Wolseley radiator grill. The 4/44 was the last car to use the engine up into mid-1956, almost a year after MG had stopped using it in the TF.

The Wolseley XPAW version had a very different sump and oil pick-up, and the dip stick on the opposite side to the MG installation. 30,000 Wolseley 4/44’s used their version of the ‘X’ series between 1952 and 1956. For the enthusiast, the 4/44’s engine was virtually identical to the YB ‘SC/2’ engine with its humble 46bhp.

The design of the ‘X’ series was very advanced for its day. Morris were in the forefront of technology as far as motor car engines go.

The cooling of the engine was carefully thought out, to keep the block hot and the exhaust valves cool. Virtually all the water flow is through the engine cylinder head, fed in from the back, exiting from the front through a temperature controlling thermostat. It was pump assisted, and did not rely on thermo-syphon alone. Later, in the TF and 4/44 the cooling system became pressurised at 4psi.

A counterbalanced crankshaft with strong connecting rods, shell bearings, renewable oil filter of the full-flow type, and valves angled towards their ports, were all good design. An oil pressurised timing chain tensioner was soon introduced, and later a modern sine-wave designed camshaft lobe, ( on the .012″ version.) As well as the cooling system being up to the minute, the lubrication was excellent, the type of oil pump fitted being easily able to cope with engine wear. Virtually all the time it was running the pump relief valve was letting excess oil back to the sump.

This was not missed by the unscrupulous, who added washers behind the relief valve spring to boost a flagging oil pressure in a worn engine. The whole engine and gearbox unit was a rigid design, with a cast iron block bolting to a cast aluminium sump, and both bolting to a cast iron gearbox at a strong bell-housing.

All this was rubber mounted for insulation at three points, and there was even a torque rod to limit engine movement. Excellent quality materials were used in the construction, and long life was guaranteed if serviced properly. Today in 1999 there are old MG’s with original XPAG engines still fitted and running well. To cope with 2000 and unleaded fuel, they will all require hardend exhaust valve seats fitting eventually.

The engine that replaced the XPAG in MG cars, was the Austin based ‘B’ series. This was initially quite a retrograde step, as it had split little ends using a pinch-bolt, split skirt pistons, diagonal big-ends, felt oil seals, a terrible manifold system and an ancient by-pass oil system that meant unfiltered oil fed all the bearings.

The first car to use it was the 1489cc MG Magnette ZA in 1953. With MG as the test-bench, the engine quickly gained a full-flow oil system, solid piston skirts, thinner piston rings, and much better oil control rings. With a bit of tuning the ‘B’ 1489cc series soon produced more bhp than the 1466cc of the TF 1500, ( 68 to 64.) Politics inside the new organisation of BMC, formed in 1953, meant Morris engines were to be dropped, and Austin engines to rule. However, a production run from 1938 to 1956 is not a bad record giving eighteen years of Morris ‘X’ Series.

Some Car Models that became available were:
Morris Oxford (Bullnose), Cowley, Morris Oxford, Major, Isis, Twenty-One / Twenty-Five, Twelve, Fourteen, Eight, Ten, Oxford, Six MS, Cowley, Isis, Mini Minor, 1100, 1300, 1800, Marina, Ital.

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Carl Wilson

You won't believe it, I'm native Scotsman. Enthusiast. Car lovers. Almost finished rebuilding my Reliant Saber 🔥


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