10v block, 20v head?

[JShadzi at aol.com]

Richard,

The NF/NG block will not replace the 7A block because of major compression 
differences.  The 20v head has a comb volume of about 49cc, the 10v 29cc.  
So, put the 10v motor in the 7A, and it would drop the compression to about 
8:1, which is fine functionally, but will be a major step back in performance 
and response.  Unfortuantely, you will need the 7A pistons, everything else 
in the block is the same- the compression differences of the pistons are the 
real differentiators between the motors.

Javad
80tq.com

In a message dated 10/23/2001 5:44:44 PM Pacific Daylight Time, 
billzcat1 at hotmail.com writes:

<< I currently have a 7A motor that I was going to build up...to minimize 
 downtime I was going to build another motor and do the swap when I was done. 
   Of course I missed the 7A that JUST went on eBay for $255.  My question:
 
 Will a 7a head bolt to an NG or NF block?  Those are both the same 
 bore/stroke and I'm hoping that they have the same kind of relationship that 
 VW 8v and 16v motors do - they are pretty much the same except the head.  
 The reason I ask: 10v blocks are way easier to find and are also way 
 cheaper.
 
 I suppose a logical question that would follow the above question would be:  
 IF and ONLY IF the NG/NF block and 7A head are compatible, do any of you 
 have a spare block lying around that you would be willing to part with?  
 Pistons, rods, crank are all trivial I don't really care if they're in or 
 out. Or whatever they are all getting replaced anyway so I guess I'd prefer 
 them gone.  Let me know what you'd take for the block.
  >>