[Spridgets] COMPRESSION

[fastvee]

I believe "Pumping" an engine measures the displacement, but I can't put my
finger on that tool. The device for checking CR is called the "Whistler", from
Katech Inc. The SCCA and many oval tracks use it for tech inspection in those
classes where specifications are limited by the rules.
http://www.katechengines.com/corporate_services/whistler.php
A bit pricey for us hobbyists, but one could be borrowed for a quick check.
Know anyone doing tech inspection at your local oval track? Then again, if the
need is just to determine what grade of gasoline to use in a street car, the
engine will tell you.
John
Fogelsville, PA

--- On Wed, 12/23/09, David Lieb <72spridget at gmail.com> wrote:

From: David Lieb <72spridget at gmail.com>
Subject: Re: [Spridgets] COMPRESSION
To: "Spridgets" <spridgets at autox.team.net>
Date: Wednesday, December 23, 2009, 9:38 AM

>     While I don't KNOW much, I would think that a compression check
>     would only tell you that the rings/piston are good. what you need
>     to know is compression VOLUME .. from the bottom of the stroke to
>     the top, added to the volume of the head. .. That is you should
>     be  looking at volume difference caused by the movement of the
>     piston, not how well it seals.

A compression test would give you some interesting, useful, but
inconclusive evidence.
I know some race groups do some they call "pumping" the engine which
can find things like that, but I do not know what all is entailed,
although I understand it is non-destructive. Anybody know more about
it?
David L
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