If you have read any of Neil Cairns’ authoritative books on M.G. Engines, you will know that the MPJG engine used in the TA was based on the old Morris 10/4 Series 2 side valve engine, but with an overhead valve conversion. This engine was initially fitted to the 1935 Morris 10/4 Series 3 (MPJM), and the Wolseley 10/40 (MPJW) cars before being used in the TA. It had a bore of 63.5mm and a stroke of 102mm, giving it a capacity of 1292cc.The stroke of 102mm goes right back to the early Morris Bullnose engines.
The MPJG engine with its long stroke, un-counterbalanced crankshaft, heavy flywheel and wet clutch, plus a cylinder head with siamesed inlet and exhaust ports, was never going to be a high revving engine. However, it did have good pulling power and loads of torque.
Now that these engines are approaching 86 years old, I frequently get requests asking if I know where there is a good TA crank for sale. Sadly, they are few and far between these days; there are still quite a few old rusty cranks about, many with cracks and ground to the maximum, so be careful buying an old one!
Such a request, 6 years ago by Mike Williams, led me to look at getting a small batch of new TA cranks made. Mike, who ran a restoration business, had good contacts with the MD of Gosnays, a long-established engineering company in Essex. At that time, I had a spare standard crank plus an old 1938 Laystall counter-balanced crank that was made for the TA Trials cars. This crank had been ground to – 60 thou and had a crack on number 4 journal. I sent both of these cranks to Adrian Wilkes of Gosnays to get a batch of 5 new counterbalanced TA cranks made. Adrian would not disclose who made them, but they did a superb job. However, they were not cheap at £1850 plus VAT each. Mike had one, as did Roger Muir and myself; I sold another one for Gosnays, but I can’t remember who to, and later Tim Parrott purchased the last one.
If you look at the photo below, which shows four crankshafts, they are from left to right: a Morris 10/4 Series 2 crank, a standard MPJG crank, the old Laystall crank used in the TA Trials cars, and the new Gosnay crank.
I have to confess that I have not used mine yet – it sits in the bottom of a wardrobe awaiting the next engine rebuild, along with a new Newman camshaft and a set of followers.
I purchased the old Morris 10 crank with a view to seeing if it could be fitted to a TA engine, the only difference is in the nose (see photo 2). This would necessitate a new crank pulley to be made to move the pulley out by 42mm to line up with the water pump and dynamo pulleys on the TA (see photo 3). Not such a big problem and second-hand Morris 10 cranks are more readily available and have probably not had such a hard life as a TA crank.
I have recently found a small engineering firm about five miles from my home, who make crankshafts, their speciality is a longer throw crank for Sunbeam Lotus engines to increase capacity. If they can make crankshafts for high-revving Lotus engines, then making TA cranks should be a piece of cake! When we come out of lock-down, I will call on them and get a quote to make another small batch of say, 6 TA counter-balanced cranks, similar to the Gosnay one (see photo 4). If you are genuinely interested, drop John an email and I will keep you informed of progress. Incidentally, one TA owner I spoke with this week was quoted £1365 plus VAT to have his old crank metal sprayed and ground back to standard size. At that price, a new crank does not sound excessively expensive. Brian Rainbow.