datsun-roadsters
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Re: Smooth breathing?

To: Victor Laury <vlaury@earthlink.net>
Subject: Re: Smooth breathing?
From: Gary McCormick <svgkm@halley.ca.essd.northgrum.com>
Date: Wed, 03 Mar 1999 07:38:49 -0800
Matching the bores when there is such a small step size, and especially
if they are smaller, rather than larger, than the phenolic blocks, is,
as some other posts mention, probably not worth the effort. Smoothing
the interior walls of the intake manifold is not desirable. Turbulent
flow in the boundary layer promotes mixing of the fuel-air mixture. You
want a nice smooth interior surface in the exhaust manifold for free
flow, but not in the intake.

Gary McCormick
'70 2000
San Jose, CA
----------------------------------------------------------
Victor Laury wrote:
> 
> Roadsterites,
> 
> I recently purchased a used SU set with manifold and air cleaner from Dave
> Murphy. I sent the carbs and hardware off to Scott of Ztherapy to perform
> his restoration magic. I took the manifold to a local shop that blasts whole
> car bodies with plastic media and now I have this beautiful, clean manifold.
> 
> The casting is very rough. I wouldn't mind smoothing out the exterior for
> appearance sake (I know, not a "stock" appearance) But it's the interior
> that concerns me. The interior is rough and the bores are at least a 32th
> smaller than the phenolitic blocks.
> 
> Does anybody know if there is an advantage to spending some time smoothing
> the passages and porting them to match the blocks?
> 
> Eastwood sells a kit for this purpose and it might make a good "watch TV
> after dinner" project <single men don't get yelled at for making a mess! and
> as sick as it might sound, I miss getting yelled at!
> 
> Victor Laury
> 70 2000
> Los Angeles

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