Morris Minor Owners Club

New 5-main blocks being made. A lot of work and a lot of expense, I guess.

Rob
Any more information?

By the time the crankshaft and con rods (and possibly a new head to suit) are made it will be very expensive.

Nissan made the 'A' Series engine under licence - one of the many changes made was to including a five bearing crankshaft arrangement.

https://en.wikipedia.org/wiki/BMC_A-series_engine

https://en.wikipedia.org/wiki/Nissan_A_engine

Nice idea but a well put together three bearing 'A' Series can rev and will rev without crankshaft whip up to very high revs with reliability included.

Phil

The short length of the 'A' series compared to other engines of its era, coupled with a pretty stout crank by small car standards will make it less prone to crank whip than most three bearing engines. If you wanted to go extreme in the hp stakes (say 150+ bhp) then you'd probably be better off investing in a strap for the centre main bearing as a precaution.

I would suggest that strapping the centre main should only be carried out on engines up to 100bhp - after that a steel 4 bolt centre main cap as fitted to my 1380cc 140bhp Minor should be used or even better have all three main caps machined out of steel.
Before I put the rev limiter on the engine I would regularly see 10,000 rpm recorded on the rev counter - the engine is fully balanced and that does cut down the engine vibration frequency.

Here is a centre main strap currently for sale on 'e' bay:-

https://www.ebay.co.uk/itm/Classic-Mini ... Sw0ohdKij3

My 1400cc Midget block (currently dismantled) is fitted with a centre main strap and I have just purchased a centre main strap for the 998cc (948cc) engine being rebuilt in slow time.

Which foundry is doing the casting———- or is it something you’ve just heard about?

Austin did a similar thing with the "Seven" engine, ie added a third bearing to the two bearing engine.
It made it even worse, the centre bearing would wear and allow the crank to flex, but the space for that centre bearing had to come from somewhere, that somewhere was the crank webs were made thinner.......The result was even more broken cranks.

A good three bearing Austin engine is very smooth..........But for how long ?

I reckon this five bearing A series could have similar problems which might outweigh any advantages.

Phil

It’s nothing more than a cad drawing at the moment, I’d be surprised if it’s ever available to buy. If you’re going to make an A series block, surely you’d start with the transverse variant?

Maybe Rob will tell us the origins and details of this revelation.