Thanks guys for your replys.
I don't quite understand what you are saying Mark.
Bosch and Siemens have a back pressure of 10 bars and Delphi 3.5 bars.
I was interested in what tolerances are allowed....would 12 bar be acceptable on a Bosch system for example.
Would 8 Bar be acceptable etc.
What is the time-factor concerning this pressure build up whilst cranking?
I can find no info on-line at all.

Thanks David that particular info came when I purchased my kit but it's very basic.

Thanks again,
Eamonn