Re: [Amc-list] 30 or 45 seats

[Greg Taylor <amundaza@xxxxxxxxx>]

Bruce,
Thanks for your feedback. on this!    I also got similar responses on the Intake valve question at www.TheAMCForum.com .  Apparently 30-degree intake seats flow better than 45, under 0.500" lift.  Stock 291c heads with 30-degree Intake seat flow 11-cfm better than a comparable 45-degree seat at 0.400" and 0.500" lift.  1 cfm = 2.056 HP, so 11 cfm = 22.6 HP more.  The corresponding torque increase would be comparable, so burn efficiency/MPG's should be slightly better at 30-degrees.  Apparently, the 30-degree seat doesn't cut down on runner velocity, as much as the 45-degree, when the flow inters the bowl and combustion chamber.
 
http://theamcforum.com/forum/forum_posts.asp?TID=7097 for answers to the seat angle question
 
http://theamcforum.com/forum/forum_posts.asp?TID=159 for Head flow specs


Sincerely, 
Greg Taylor :) <>< 
Rochester Hills, MI
1989 Jeep Grand Wagoneer "TRMN8R2"

And the testimony is this, that God has given us eternal life, and this life is in His Son. He who has the Son has the life; he who does not have the Son of God does not have the life. - 1 John 5:11-12


--- On Wed, 10/29/08, Bruce Hevner <scramblr@xxxxxxxxxxx> wrote:

From: Bruce Hevner <scramblr@xxxxxxxxxxx>
Subject: [Amc-list] 30 or 45 seats
To: amc-list@xxxxxxxxxxxx
Date: Wednesday, October 29, 2008, 10:35 PM

Generally speaking 30 degree seats will flow slightly more at low lift (say
.250 or so and less) than 45 will due to less valve shrouding by the valve
itself. They also tend to wear the seat less due to less sliding action as
the valve opens and closes.
Unless it's a stock valve job I change all my seats to 45'. Most of the
time the valves will be replaced so that 1 piece valves will be used. To my
knowledge MOST HP valves are supplied in 45'.
But HEY,,, that's just ME
Bruce Hevner


      
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