What is the difference between the b230 700 series 4 banger cyl head, and the B23 engine in the 240?

Also was there any variation whatsoever of the B23 head in different years, and same for the B230.

Also does the 16 valve head fit on any block piston combination (say a b21F or a b23) or does it notwork/make it an interference.

Thanks.

Oh yah, and the difference between the B21 head in 240s and the B23 in 240s head is?

There were several different castings for B21/23/230 heads.

The 160 was the one used on nearly all B21s. It has holes in the head for the K-Jet injectors. The 405 was used mostly on B23s, with K-Jet injection, but a few were made with blank bosses for use with LH-Jet (injectors in the intake manifold.) The 405 has a slightly larger combustion chamber and 'swan-neck' ports that flow better than the 160, 398, or 530. The 398 was used on B23s, mostly with LH-Jet, and had the same port style and combustion chamber size as the 160 head. The 530 was the standard head for the B230, similar to the 398 (LH-Jet.) The 531 was the best Volvo made, swan-neck ports and a larger combustion chamber like the 405, and a slightly more central spark plug location, and LH-Jet compatible. There is also a bizarrre head with no combustion chambers. I know nothing about this one...

Turbo heads also had sodium-cooled valves.

The best you'll find in the U.S. is a 530. We never got a 405 or 531-equipped Volvo here. Canada got some 405s. 531 is Europe-only.

There is an article on Turbobricks with some more specifics.

Ok I had a 405.

I need to get a 531, but first will attempt to get another 405.

Your post basically told me everything I need to know about every head, which is greatly appreciated!