Date:         Tue, 12 Feb 2002 16:43:00 -0500
Reply-To:     "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
Organization: Bulley-Hewlett
Subject:      Help setting deck height on Type 4 motor
In-Reply-To:  <v0422080bb88f20eb0ce2@[207.23.94.149]>
Content-Type: text/plain; charset="US-ASCII"

Howdy all--

I have a semi-stock Type 4 motor in my 1982 Vanagon for which I need a
little guidance setting the deck height. Here is what I know.

The motor has a stock dimension counter-weighted crank, stock (balanced)
rods, stock heads (very slightly flycut), and set of slip-in, flat-top
96mm NPR piston/cylinders. I built it a few years ago and have a few
thousand miles on the motor; today it has developed a head-to cylinder
'chirp' under full-throttle, low-speed acceleration that indicates a
compression leak.

I did not use in-head seals or barrel shims, but the deck height
(eyeballed) was within .5 mm of the top of the cylinder. Between the
flycut on the heads, and the flat-top pistons, it would appear the
compression ratio is too high.

The initial compression test (within 2k miles of building) indicated
about 160 psi all around. However, the compression test now everything
has settled in, (about 9k) indicates the compression is way high, at 185
on two cylinders, and 170 on the others. I'm going to pull the motor
replace the rings, and shim the barrels.

My books give no help. How does one set the compression/deck height
accurately, considering the modifications to this motor?

From historic, walkable Mount Olive, NC,

G. Matthew Bulley
Bulley-Hewlett
Corporate Communications
Business: www.bulley-hewlett.com
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Home: www.MountOliveNC.info