BMC B series race engine

I seem to remember that later versions had a 5 bearing crank, which was better for more extreme tuning.

I think the changeover date was 1970 so there are few 3 bearing engines around. There were a number of other changes made, mainly subtle such as the camshaft moving downwards requiring a shorter chain.

The joys of the three bearing crank. Two mates and I ran Victor 101 estates in the 70's. We all had to replace main bearings, and one of us broke a crank half way back from the ferry after his summer holiday camping in France. I had to get up at 2 am to rescue his family, and then back to tow it the next day.

In the late 1960's Dad had a crank snap in a Triumph 2000 (6) while running in.

But he was brought up in an age where people had a fear of high rpm and running in was supposed to be "gentle" so he may have been lugging it.

BMC did a 'special tuning' booklet for it in the day. I'd guess you might find it online.

Very expensive to get any real power out of, though. As it will break if you increase the rev limit in standard form. Some decent head work and a good mild cam will get about 120 bhp.

I'm not aware of it being raced seriously. However it should be a pretty strong engine as the 1.8 desel is closely based on the same block.

It's also has Siamese ports that are not conducive to faster cams. Perhaps a large HIF carb or injection might help match mixture on the inner and outer pots.

What I might suggest is lookup the methods used to tune A-series engines sine the engines are similar.

I agree the head is the first place to look at, also the valve springs weren't fit for purpose and so limit revs.

If you want power then it was more typical to go direct to the V8.

Or get an MgC ?

Or fit a more modern Japanese DOHC 4 pot.

Plenty of them to chose from 120bhp for N/A up to 200bhp for turbo versions. Mazda and Nissan from around 1990's have simple EFI systems before body system integration. Usually only about 5/6 connections to main loom. Power, switched power, gound, tach, speed and mil.

May need to stitch weld the chassis, the old rusty spot-welds have been known let go with decent power.