Distributors between the A Series and A+ engines are not interchangeable.
The A Series Engine uses a 45D or 25D Distributor
The A+ Engine uses a 59D or 65D Distributor
Mini A Series Distributors (up to 1980) are held in place by a pinch clamp and 2 bolts.
Mini A + Distributors are held in place by a Y clamp and a single bolt.
To identify the difference between these two engines, read on…!
Much has been written about the A Series engine, and one of the best articles is this one written by AROnline founder Keith Adams. It’s a great place to read more detail about the ins and outs of the A Series engine and it’s history and development.
The A+ engine came on to the mini scene in 1983. It has a thicker block to box flange and is generally more robust than the standard A series. Operationally it’s pretty much identical and is the same capacity. Heads/boxes are swappable.
Here are the A+ distinguishing features:
• Strengthening ribs on the back of the block at the clutch end
• Thicker block-gearbox flange
• Dizzy clamp is a forked plate with a single bolt into the block
• Dipstick sits directly in block, not in a tube, and is shorter
• Verto clutch, slave on plate slanting downwards, short arm. (NOTE: The very first A+ engines had a pre-verto clutch)
• Alternator bracket mounting holes are closer to the rad on the A block
• ‘A+’ stickers on rocker cover if a Metro!
NOTE: The 1275 crank fouls the inside of the gearbox casting on earlier 1960s unless the ‘box came off an “S” originally.
They standardised in ’68 or ’69. The changeover to A+ didn’t occur on all parts at once. Some engines had eg: A+ block and pre-verto clutch, and some had A block/box and A+ bits bolted on. Maybe BL running down stock.
One correspondent has an A+ engine as described above, but it was the original engine from a 1981 New Zealand model 1275GT. It does not have a verto clutch, but the gearbox is the A+ type, and so is the block. It could have just been a test by Austin-Rover to see if their engine was any good before it was released in the UK in 1983.
It is possible to put an A series engine onto an A+ gearbox and vice versa, but the transfer housing and drop gears *MUST* be the same type as the gearbox, as the idler bearings are different sizes. Apart from that nothing to it.
Our own internal engine number check page
Home brew Engine Decoder shows weather you have A series or A+
Usually the years apply but bear in mind engines are commonly swapped and so please confirm with the engine number where possible or failing that please rmeove the distrbutor and confirm visually by looking at the gear and comparing wiht this image below. A Series and A+ Distributor Drive differences:
