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post #12 of (permalink) Old 5th December 2007
Technical Supremo

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Hi Hudson -are you sure you are reading the compression tester correctly - Not sure exactly what the compression pressure should be on your engine but as a guide to what is ideal you do a simple calculation as shown below.

Compression Ratio of engine X normal air pressure

For example for an engine having a compression ratio of 10 to 1 and normal air pressure is 14.5 psi - the following simple formula is OK

10 x 14.5 = 145 PSI

Could it be you are reading the "Bar" scale of the tester?
One other possibility is that you ccould have a sticking valve (which would give a clicking sound) - may be worth giving the engine a shot of Redex or the like.
A leak down test is where each cylinder is pressurised and the time noted on how long each cylinder takes to loose all pressure - in many ways it is a more accurate test of compression.
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