Hello
All,
It
is true that the 915 heads do not have the best valve size and port areas. However,
and this is a big however, it has been discovered over the years that
detonation is not only a factor of compression ratio, but also something called
the quench area. And the 915 heads have one of the best quench areas of big
block heads, due to their closed chamber design. Please see the articles
linked below.
http://www.moparmusclemagazine.com/techarticles/mopp_060800_mopar_max_wedge_cylinder_heads/factory_parts.html
http://www.moparts.com/Tech/Archive/motor/15.html
If
anyone would like to trade their 915’s for open chamber heads, I would be
happy to acquire them.
Tom
From:
mailing-list-owner@xxxxxxxxxxxxxxxx [mailto:mailing-list-owner@xxxxxxxxxxxxxxxx]
On Behalf Of Bob
Sent: Thursday, February 21, 2008 5:37 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: Re: IML: 1967 440 and trans {big valve heads}
I
was going by word of mouth. Glad theres people out there who know their
stuff. I learned something today. I always enjoy reading info like that. Helps
for future refrence. Thanks for the effort.
-----
Original Message -----
Sent: Thursday, February
21, 2008 7:20 PM
Subject: Re: IML: 1967 440
and trans {big valve heads}
915 heads don't do an Imperial owner any good except for
bragging rights, and the pain may not be worth it. We're talking about a
compression ratio greater than 10:1, requiring great care to avoid preignition
and/or detonation with today's pig slop gasoline. In addition, the larger
valve sizes are of negligible benefit at an Imperial's normal RPM range (below
4000). Even racers know the 915 heads don't flow as well at high RPM as
the later heads that came with larger valves. This engine combo is best
suited for somebody trying to do a correct restoration of a car that came with
it from the factory. Those of us who like to drive our cars a lot need
later open-chamber heads. Compression ratio is lower, the valves are
larger -- paint them Mopar turquoise and only an expert can tell from the
outside that they're not year correct for your car.
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