<VV> Shimming of Heads

[jryall at juno.com]

Back in the old days of no high test and the beginnings of no lead in the
fuel, some people shimmed the bottom of the cylinder to reduce
compression in order to run the lower octane fuel.  Shims were put at the
bottom of the cylinder because a shim at the top or double stacking
gaskets was thought to make a hot spot.  There was a lot of confusion
about no lead until it was shown that our engines could run on it and not
suffer from valve/seat problems.  I was lucky enough to have a Getty
station near me (AFAIK they were the only ones to carry high test during
that period) and never changed a thing.

Now we use the gaskets when heads require remachining in the gasket area
to achieve the desired compression ratio or to adjust the gap in the
squish area for turbulence in the combustion chamber..

John Ryall

On Wed, 16 Feb 2005 10:24:33 -0800 "Ron" <ronh@owt.com> writes:
> Then how come the vendors have been selling a selection of copper 
> head 
> gaskets for years?  You can buy any thickness you need.
> RonH