I have also been intrigued by these devices, but have never seen one.
The device you describe would not give accurate readings, unless the intake
& exhaust valves were disabled. Otherwise, valve timing would affect the
measurement & render the results useless. Do you recall if the vales were
disabled during the test?
Perhaps this is why OHC engines require a different tester? On a pushrod
engine, I suppose the valves might be conveniently disabled by backing off
the adjusters, removing rocker arms, or removing pushrods. But not so on an
>CC: email@example.com (Cris Vandagriff), firstname.lastname@example.org
>Subject: Re: HMSA, pump rattling
>Date: Tue, 22 Feb 2000 18:02:19 EST
>In a message dated 02/21/2000 10:42:10 PM Pacific Standard Time,
><< I dont know how these tools work and but I am especially intrigued by
> difference there could be between a procedure for overhead cam engines
> one for pushrod engines. >>
>once upon a time the SCCA used a plastic tube with a sliding slug inside
>a hose that connected to the cylinder via the sparkplug hole. Cranking the
>motor over slid the slug up and down the calibrated plastic tube indicating
>the approximate cc's of the cylinder. As you speculated, it didn't know if
>was a 4 valve or a flathead.
>850cc Enfo Coffield Mk.III