Re pump rattling: Hi Mark, I was pumped at the Monterrey Historics a couple
of years ago. I presume at the request of one of my fellow competitors. The
Lister Chevy passed the test and pumped to the 339cid declarde on the entry.
This is what you get with a stroked 283cid motor. You are correct in that
the inlet and exhaust valves must be closed to do the test. This is easy on
a pushrod motor, but more difficult on an overhead cam motor. A thermometer
is used to determine the temperature of the cylinder at the time of the
test. All of the data is fed into a formula which give a pretty exact
determination of the motor"s displacment, when multiplied by the number of
cylinders.
----- Original Message -----
From: Mark Palmer <mgvrmark@hotmail.com>
To: <EeeMCee@cs.com>
Cc: <vintage-race@autox.team.net>
Sent: Sunday, February 27, 2000 1:48 PM
Subject: Re: HMSA, pump rattling
> Michael,
>
> 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
> OHC.
>
> Comments?
>
> Regards,
> Mark Palmer
>
> >From: EeeMCee@cs.com
> >Reply-To: EeeMCee@cs.com
> >To: malcox@napanet.net
> >CC: hmsa@email.msn.com (Cris Vandagriff), vintage-race@autox.team.net
> >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,
> >malcox@napanet.net writes:
> >
> ><< I dont know how these tools work and but I am especially intrigued by
> >what
> > difference there could be between a procedure for overhead cam engines
> >and
> > one for pushrod engines. >>
> >once upon a time the SCCA used a plastic tube with a sliding slug inside
> >and
> >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
> >it
> >was a 4 valve or a flathead.
> >Michael
> >850cc Enfo Coffield Mk.III
>
>
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