Monkey......What we 'think' is correct, and what 'is' correct just might 'be' 2 different things.
The throttle must also be held open. Check here:
http://www.aa1car.com/library/compression.htm
5. Block the throttle open. Check here:
http://www.georgiazclub.com/tips/ztech/comptest.htm
Hold the throttle to full open position to ensure the engine gets adequate air intake. Check here:
http://www.motorage.com/motorage/art...l.jsp?id=16170
Open the throttle fully either by pressing the accelerator or wedging the linkage open under the bonnet. If the throttle isn't open then adequate air can't get into the cylinder and the readings will be far too low. Check here:
http://www.pumaracing.co.uk/comp.htm
I've found thru 22 years as an ASE Master Tech, specializing in engine diagnostics, that simply 'asking' about a procedure can get you correct information much easier than 'asserting' what you think is correct in an "I know better" way.
IHateHacks language may sound a bit rough, but is to the point.
As a technical training instructor for several years, I learned a lot about 'presenting' information to students.
I prefer to back it up with references.
Simply put: Research, analyse, ask and resolve any questions, understand, know.
PS: Google is your friend !