I have a Dellorto 45 sidedraft carburettor, a modified Kent 296 camshaft, Powermax 73.5 mm pistons on shotpiened rods, a nitrided crank and a stage 4 12g940 cyclinder head with around 10:1 compression. This engine is one of the more powerful in my Club (Mini Car Club of Auckland). It was the most powerful car at the last dyno shootout we had, although some of the more powerful cars in the club didn't turn up.
I bought this engine in a car in a rather sad state. It had been damaged either by overheating or improper running in. The rings were not sealing as they should, and the head gasket had blown between 2 and 3 cyclinders. I had it profesionally rebuilt, as I was not confidant to do it myself at the time. This was rather expensive!. The engine turned out to be very powerful with a new cam in it.
It ate a differential soon after I installed it. It turned out that the gearbox I installed was rather worn. It required a new layshaft and bearings, new first motion shaft, mainshaft and little bearing that goes between them, but worse, it needed a new double row bearing. The cage had fallen out, allowing the balls to hit each other. This meant that what started as a simple diff replace turned out to be a whole gearbox rebuild. My friend Frits lent me a gearbox while I rebuilt mine.
If you have a powerful motor and a standard diff, you want to read why the standard diff is so weak.
Unfortunatly in 1999 my 1380 engine dropped a valve :-/
I quickly replaced it with the spare engine, which is a rather tired 998cc unit that I have in the garage for just such emergencies. While questing for more speed, I installed a 12G940 head.
The 1380 is now rebuilt and operating again which is nice. I am currently investigating installing a vaccume advance. The Dellorto DHLA45 does not have provision for a vacuum advance so I have to use a direct connection to the manifold. I have yet to take the plunge and impliment it. I still intend to do an electronic ignition, but I figure a vacume advance is better than nothing and will hopefully improve the fuel consumption.