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Port sizes on Holbay and Stock

To: alpines@autox.team.net
Subject: Port sizes on Holbay and Stock
From: Jay_Laifman@countrywide.com
Date: Fri, 9 Mar 2001 08:04:43 -0800
tom.hill@att.net writes:
>>The Holbay intake port is the same size as the standard
>>exhaust port.

Christopher responds:
>Huh?  That doesn't seem right.  How does the head breath
>with an intake only, what, 1.2"?  I can't recall the stock
>size, I seem to recall about 1.4" for the intake & 1.2" for
>the exaust.

I happen to have my figures from mine here at work.  Tom, my measurements
were different than yours.

Here is what I have:
Stock Exhaust Port 1.12 inches
Stock Exhaust Manifold 1.12 inches
Holbay Exhaust Port 1.21 inches  (note the step if putting stock exhaust on
Holbay head)

Holbay inlet 1.16 inches
Weber outlet 1.2 inches

As I mentioned before, it is well documented that Rootes reduced the size
of the Holbay head inlet to get better low end response.  My mechanic said
this was not necessary and opened up my Holbay inlet to match the Webers.
I am very happy with my low end response.

Jay

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