Re: Numbers, any one?

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: Tom Jennings <tomj@xxxxxxx>
" 
" On Sat, 16 Jul 2005, Sandwich Maker wrote:
" 
" > it'll -fit- '64-'72, but i bet it's more exactly the '64-'67 closed
" > chamber head.  iirc the '68-'72 head had very different open chambers.
" 
" Excuse my ignorance, but what is the difference between open and
" closed combustion chambers?

an open chamber is a more-or-less smooth bowl the full diameter of the
cylinders.  a closed chamber can be any shape that doesn't cover the
full cylinder diameter.  this leaves 'squish' area where the piston
closely approaches the head.

big block chevy open chamber heads flow better and make more hp, but
because of the squish which promotes turbulence and rapid burning,
closed chamber heads are usually more efficient.  squish, or 'quench'
can also stifle complete combustion, increasing emissions.

for amc sixes, the '64-7 closed chamber head had ~56cc chambers.  the
'68-76 heads had ~66cc open chambers; '77-9 had ~74cc open chambers.
i don't know about '80s heads but iirc c/r crept up over the decade
from 8:1 to 8.6:1 to 9.2:1, with the same pistons.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen

adh@xxxxxxxxxxxxxxxxx                       and think what none thought