Actually Head porting is lots of things to lots of people.... but the
correct manner in which it is done is through careful study of what the
requirements of the engine are for airflow with a Given cam.... and also the
designed requirements of an engine.
The First and easiest step in Head Porting is Port matching gaskets.... that
is making the mating surfaces have the same size holes on the head and the
intake and exhaust manifolds...
the second step involves pocket porting around the Base of the valve and
messaging the cumbustion chamber itself....and ultimately enlarging the
Ports flowing to and from the Head.
To do this correctly you have to have a Flow Bench and match each port the
others... again any increase in Flow has to be EQUAL in all cylinders....
and that flow has to be matched to an RPM range in which the engine is going
to run. Not only that but the Flow has to be equal at any given point in
the ports cross sectional area....
Okay confused... Good... seriously this is a very fine science and for the
average performance of a motor I wouldn't recommend Lots of Port Work....
All I would do is Port Match the exhaust side...( as I recall the intake has
sleeves that make it port matched already ) and I would clean up any
obviously large flaws in the casting of the exhaust manifolds.... then I
would lightly work the combustion chamber itself to make sure there are no
sharp points which might enhance the opportunity for pre-ignition.... and
generally clean up the ports themselves with a sanding roll and move on....
I am talking not more then 20 min per cylinder work here... and Keep your
sanding roll off the valve seats as you are going to have them done AFTER
you do this....
Keith Turk ( and NO I dont' have a clue... but I have done a couple of LBC
heads this way and I know I have improved performance a Bit... and haven't
HURT anything )
----- Original Message -----
From "Jeffrey H. Boatright" <jboatri at emory.edu>
To: <spridgets@autox.team.net>
Sent: Thursday, January 11, 2001 6:35 AM
Subject: Re:
> From my limited experience and reading the usual suspects, this is
> only partially correct in that the word "porting" often is used to
> mean more than reworking the intake and exhaust ports of a head.
> Porting often is used when one is speaking of also reworking the
> head's combustion chamber, including and especially the area around
> the valves. Those changes don't require matching to the manifolds.
>
>
> DLancer7676@cs.com wrote:
> >In a message dated 1/11/2001 12:48:07 AM Eastern Standard Time,
> >barryk@cableone.net writes:
> >
> ><< I am looking for performance parts for a 1275. Pieces like a ported
head >>
> >
> >I don't think just a ported head would do you any good. As I understand
it,
> >and I have never attempted to port a head, the head is ported to match
the
> >accompanying intake and exhaust manifold. I think I understand how it is
> >done, and am sure I will be porting a head in my future. I think you
would
> >be best to use your stock head and port it to YOUR inlet and outlet
> >equipment. Is this correct, listers?
> >
> >--David C.
>
> --
>
>
> __________________________________________________
> Jeffrey H. Boatright, PhD
> Assistant Professor, Emory Eye Center, Atlanta, GA
> Senior Editor, Molecular Vision
> <http://www.molvis.org/molvis>
> <mailto: jboatri@emory.edu>
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