I am wanting to build an L20B. i have a complete engine to replace my L18.
Plans are for increased compression from 8.5 to around 9.8 to 1. mild cam and headers.
Is it worth using my L18 head, it was rebuilt 20,0o0ks ago, or completely rebuild the L20B.

L18 head is already higher compression so that would be a good start, especially as it has already been rebuilt

Keep the L18 head - especially if it is an A87.
Cheers

the3 head is a W53. the head on the L20B is a U67.
are they any good?

i have a some L20b extractors and it might even have a small cam (don't quote me) that u can buy, comes with a free bluebird

I think but am not 100% sure that the W53 head was fitted to the later L18s, ie the 810 180Bs not the 610 180Bs which had the A87 head. The U67 is the standard L20B head and is open chamber and hence low comp.
An A87 head on an L20B block gives good compression, probably a little bit more than you mentioned you were after. W53 is probably a similar story. I will have a look in the Honsowetz book to see what it says about the W53. rob240z from the NZ site reconditioned the SSS L18 in his 180B SSS P810 and that has a W53 so I will ask him for you. I think they are a peanut chamber head with the same size valves as the A87 and U67.

thamks for that.
unless something else comes up to change my mind, ie ypu say the W53 is better, i will be going with the L20B with the U67 head, Extractors and rejetted carb with a com ratio around 9.5 to 1.