don't need new timing belts, they can have their valves adjusted
without gettings shims, and because if you overheat one you
don't need to have the head skimmed.>

You'd seriously rather change a timing gear than a belt?

I reckon the B21 is a development of the B18/20 with the faults ironed out. The later engines are significantly more economical, on the whole easier to service, and nigh on bullet proof.

I don't reckon there's much to choose between them though, leaving out the B30. The overheating argument is just plain silly. Sure an aluminium head will warp, but then the rings break on a B18/20 and ruin the bores if you cook it.

By the way early B18's had a nasty habit of shearing the pin holding the hear onto the oil pump drive, not nice.

Its sort of like comparing Peaches and Nectarines, they're just different.


Regards


Pete