Date:         Fri, 24 Feb 95 8:11:20 MST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         aburczyk@dres.dnd.ca
Subject:      Re: Pilot Bearing...Out!, Another Question

The thin metal gaskets are actually shims that go between the case and the 
bottom of the cylinders. They are designed to adjust the final compression 
ratio of the cylinders to the specification of 7.3 to 1. Note that there are 
2 types of pistons on the market right now for the type 4 (bus, type 4, and 
porsche 914) engines.  On high compression engines there is a raised plateau 
on the piston crown on low compression (ie bus) engines there is a flat 
depression on the piston crowns.  DO NOT USE THE HIGH COMPRESSION PISTONS. 
I did this last year on a rebuild and after 3000 miles melted #4 piston (The 
one next to the oil cooler.).  On autopsy I back calculated the compression 
ration that I had built into the engine at 8.83 to 1.  This is why I had to 
burn at least 94 octane gas (It still pinged) and the advance on the 009 
distibutor didn't work very well any more.  I am currently rebuilding the 
engine again with the proper pistons this time.  I have also cc'ed the head 
volumes individually (to calculate the TDC volumes) to make sure that the 
spacers and head gasket that i use will give me as close to the stock 
compression ratio as possible.  I will also make damn sure that #4 has 
the lowest compression ratio of the lot.  You also have to have the 
same number of cylinder spacers on each side of the engine so that the 
head sits flat on the head gasket rings as well.  In calculating the 
compression ratio don't forget to account for the thickness of the head 
gasket, since it crushes down you must use the thickness of a "squeezed" 
used gasket in calculations.

Oh yes if anyone has the pistons with raised crowns it takes about a 2mm 
cylinder shim thickness to get back to about the stock compression ratio.

Take nothing for granted, for the perversity of the universe tends to a maximum.

A. Burczyk

aburczyk@dres.dnd.ca

> 
> It worked, it worked
> 
> Took a while to file that washer just right, and it took a lot of force ,
> but the remains of the bearing finally squeeked out of the end of the
> crank.
> 
> I promptly hammered in the replacement bearing.
> 
> Next question.
> 
> The gasket kit I have includes 2 sets of 4 metal sealing rings.  The
> thicker, less flexible rings go  -between-  the top of the cylinders and
> the heads.
> 
> My question is about the thinner, very flexible rings.  These could
> conceivably go -around- the crankcase end of the cylinders, or -around-
> the head end.  Which is the right location, and are these rings necessary?
> 
>  Peter Williams
> 73 Westy (1700)
> California or Bussed
> 
> 
>