The test is designed to measure the amount of cylinder pressure of an
individual cylinder.... Take all the plugs out and like Peter says Throttle
wide open...
Your looking for the max a cylinder will give and that they be within 10%
of each other... they may be equally worn out so you should have at least
110 psi on a High Compression 1275.... don't know what a Low compression
is...
and this is truly an opinion...
the wet test basically means to add oil to the cylinder... table spoon or
so.. I use a Syringe and about 10cc.... yeah I know it's alot... but I want
to seal the rings and check compression again... on a wet compression
check if the pressure doesn't rise there is a very strong possibility of a
burnt valve... or a leaky head gasket...
The only way you can get a real check on the rings is with a Leak down
checker... which measures the amount of air that will pass the rings when
compressed air is applied to it with the valves closed....
Keep in mind starting a motor that has been sitting for a while is tough on
the rings as there maybe some light rust in the bores... let these things
wear a little before you worry much about the compression.. Long as it has
some compression it should start...
All that having been said what I do when I buy a car... or like the race
car... I take a base line and write it in the Manual I have for that car..
I did this with the Hundred when I first rebuilt the motor and have had
that base line as a bench mark for 20 years... now if I get less then that
I know I have wear...
On the race car I have starter buttons on both sides of the firewall just
to make it simpler... mostly to adjust the valves but I use it to bump
around the motor on a leak down also... With a .680 lift roller cam the
it's not hard to tell if it's open...or closed...
Keith Turk
Austin Healey 100 / Bugeye / Box Sprite / Bonneville Land Speed Racer
Camaro ( D Gas Altered )
----------
> From: LBCarNut@aol.com
> To: bjschief@acay.com.au; spridgets@autox.team.net
> Subject: Re: Compression testing
> Date: Sunday, July 25, 1999 4:26 AM
>
> In a message dated 7/25/99 3:24:29 AM Eastern Daylight Time,
> bjschief@acay.com.au writes:
>
> > I have bought a compression tester, but have been
> > given conflicting advice on how to carry out the test. Is it better
to
> > test by removing one plug and firing up the engine (on three
cylinders) for
> > a couple of seconds, test with three plugs in but only using the
starter
> > motor to turn the engine, or to remove all plugs and test each
cylinder
> > using the starter motor only ?
>
> The standard test is engine warmed up, all plugs removed, throttle wide
open,
> crank the engine until reading quits rising.
> That being said the main thing you are looking for is consistency across
the
> cylinders.
> Regards,
> Peter S.
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