[Shotimes] Gasket Matching on the Intake

[sho2go]

A very long time ago, and in another galaxy, it seems, I was working on
small bl. Chevs (1970's).  Haven't done much since, so my experience may be
sadly outdated.  But as I recall simply opening up ports, valves, head
passages etc. without a flow bench often resulted in worse performance than
stock.  Just one guy's 2 cents.
Mike

----- Original Message -----
From: "Kurt M" <kmetros@elkhart.net>
To: <TechSHO@topica.com>; "'shotimes'" <shotimes@autox.team.net>
Sent: Monday, February 10, 2003 3:15 AM
Subject: [Shotimes] Gasket Matching on the Intake


> A couple of years ago when I had my SHO apart for it's second 60K I
> ported out the leading end of the intake runners to match the gaskets
> between them and the butterflies.  When I was done, the opening was as
> large as the gasket and was tapered about 1.5" into the snakes, after
> which the went to their normal size.  I also opened the holes in the
> surge tanks to match the gaskets.
>
> At that time I didn't mess with the openings between the snakes and the
> heads.  This year, while it's apart, I am considering using a dremel to
> port out the intake runners to match them to the size of the intake to
> head gasket.  I am also willing to port out the heads to match these
> gaskets.  Until yesterday, I wasn't willing to do this, but now that I
> have the intake off and have looked at it more closely, I have a better
> idea of how people are doing this with the heads still on the car and am
> willing to try it out.
>
> In reading about porting on the web, a couple of things came up that
> cause me to question  whether or not this would be a good or bad thing
> to do to my intake and heads.  My main concern seems to be that of
> velocity.  Let's say the intake opening throughout the snake is 'x'
> (where x is some volume of air, or some unit of measurement with regards
> to the size of the opening) until 3" before the air hits the valves,
> then for the last 3" (the area I port out on the snakes and head) the
> volume becomes 'y' (some measurement slightly larger than x), will there
> be enough loss of air velocity in the last 3" due to the larger chamber
> size to cause a negative effect?
>
> I'm wondering if this mod shouldn't only be done on an extrude honed
> intake, where the size of the intake snakes are the same from the surge
> tanks all the way through to the heads, where the size isn't going from
> smaller to larger?
>
> Am I on the right track?  BTW, here's an excellent article I found on
> porting....
>
> http://www.sa-motorsports.com/portdiy/diyport.pdf
>
> Input appreciated.....
>
> Kurt
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