Engine compression test E TYPE v12 1973

Gerard ,
The general rule for cylinder cranking prussure is 14.7 multiplied by the compression ratio of the engine. An example is; 10:1 compression times 14.7 = 147 pounds per square inch. Lots of things enter into this, and is not an exact number, but should get you close.
Pehaps a more exacting way is to do a leak-down test by putting 100 lbs. of air onto the cylinder and measure the percent of leakage.
Keith

WD40 is not the best stuff for your aluminum pistons, or other stuff in the engine lubrication system like the bearings. Some 30W motor oil would be best. Oil will raise your compression test readings somewhat, depending on how much oil you use, and how long since you squirted it in each cylinder.

WD40 has a very high chlorinated content, and can be corrosive at a microscopic level leading to coating loss, wear, or cracking, especially on non-ferrous materials like used in pistons, platings on piston rings, O rings, and lead/indium bearing shells for cams, pistons, and crankshafts.

Use of that stuff is outlawed on military aircraft engine hardware for this reason. We were told that 'WD' stood for water displacement, and it was designed to be highly reactive for unfreezing corroded steel bolts. Anything you resorted to WD40 to get apart had to be scrapped or promptly chemically cleaned in approved cleaning solutions.

I did lubricate the cylinders with WD40 and the intake manifolds have bee removed
I turned the engine between 5 and 10 turns
Do you know what is the "regular" Compression ?
Thanks
Gerard

Did you lubricate the cylinders before turning the engine? If not do so. Then do the test again; disconnect the ignition feed, have someone hold the acc pedal open then turn the engine over 5 turns ON EACH CYLINDER and see what you get.