[Amc-list] Machine Shop Recommendations

["Larry R. Daum" <mramc@xxxxxxxxxxx>]

Date: Fri, 12 Oct 2007 23:32:06 -0400
From: "Bruce Hevner" <scramblr@xxxxxxxxxxx>
Subject: [Amc-list] Machine Shop Recommendations
To: <amc-list@xxxxxxxxxxxx>
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 >another  highly recommended option, convert the semi open AMC head to

full open chambers head. I can post or >email the specs to you or any one
else who wants it from the old Performance American style manual . Trade
off >is some where around a .5 point drop in compression ratio. This
depends on what compression ratio and heads >you intend to run, stock
square port or dogleg. thanks, LRDaum

I believe you are incorrect in recommending this!! What the book means
(and I still have mine) is to open the part of the chamber that misses the
cylinder bore. It should be opened up to match the cylinder bore. NOT to
"full open chamber" the head. This would mean removing the "Quench" area
of the head which is VERY important !!!!
  I still have a set of 390 heads that have had this mod done to them. If I
were doing another set I would only match the exhaust side of the head. I
don't believe doing the intake side will help much if any.
  That book was done YEARS ago before we had the flow knowledge that we do
today. The intake side of the combustion chamber on an AMC head has very
little shrouding.
What I have seen on AMC heads is the seats being sunk below the surface of
the combustion chamber. I am a believer in "low lift flow" so I machine
the floor of the combustion chamber to match the 45' angle of the seats.
This does make the chambers bigger so you have to watch your compression.
With a set of TRW flat top 2 relief pistons at "0" deck I ended up with
11.2-1 on the 390 they were used on.
  Email me if you would like photos of the heads.
Bruce Hevner

Bruce,
I recommended this as optional mostly as a means of lowering  compression if
needed. Also I believe we may have different defections of what full 
open versus
semi open head is. My understanding is that AMC use it's standard semi -open
combustion chamber head for emissions reasons. I did note that it 
depends on which heads
you use , along with which pistons. But it a mote point as no one 
seems interested in it.
At least no one email me interested in it. Yes, the old AMC 
performance book was done
years ago and yes we have improved our knowledge of air flow.   LRDaum


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