Chop the grot
Rot around the rear screen calls for some careful thinking.
In the previous issue I spoke of my plan for world domination by supercharged Morris Minor. Before getting too carried away, however, there was the little issue of rot around the rear screen. This was most concerning as the corrosion, caused by a leaky rubber, had taken hold behind the complex ‘D’ section of the roof where multiple panels meet.
I’d sourced a replacement lower section of roof for this area from a club member who’d cut it out of a scrap car, but tackling the job wasn’t one I was at all looking forward to. One of the most important and difficult tasks was understanding the construction of this area in order to work out the best places to cut to preserve datum points and the integrity of the shell. I removed the rear windows and cleaned up the apertures so as to weld strengthening bars in to hold the roof still when the C-pillars were cut. Having marked the area to be chopped out I lost my nerve and set about stripping down the engine instead. Ignoring the elephant in the workshop, I secured the engine to a stand. Disassembly was straightforward and comfortable. I’ve never used an engine stand for an A-series before, instead opting to heft the block around by hand. Even though it’s only a small and relatively light engine I was astounded at the difference working on an engine stand made to the overall experience. Much more pleasant and far safer. The engine itself tells a story. It’s a 1275 A+ unit that I’d fitted in 2015 shortly before the annual Minors on Tour holiday – the 2015 tour was to the Ardeche in the south of France the day after my final university exam. From the off the engine smoked, so with only a couple of days to spare before the trip I pulled it
apart in a hurry, quickly ran a glaze-buster up the bores and replaced rings and bearings before refitting it to the car. Under mild load on the running in process the refreshed engine performed well, however problems began to arise as soon as we had crossed the English Channel. It was breathing very heavily and, to cut a long story short, used six gallons of oil that holiday – it came off the road not long after.
I knew, therefore, that the internals wouldn’t be in a very good state. I was right. The new bearings had clearly suffered from the oil starvation that they’d received on the trip, as had the crank. Four broken top piston rings – either a consequence or the cause of the issues – told a story of their own.
All in all, the engine will require a total rebuild, but there is some good news; the cylinders have been fitted with liners that bring the bores down to standard size – potentially signifying it as a factory-reconditioned unit. If I can get away with just a hone, then the original pistons with an 8cc dish may be able to be reused, saving a good chunk of money.
Back to the job in hand
With this dish, then it’s eminently feasible to open out the ports of the 12G940 cylinder head to around 26cc each meaning an 8.5:1 compression for forced induction can be possible without the use of a decompression plate. Which sounds very good to me.