Say I perform a cranking compression test on a nice day with high barometric pressure vs. a day when it's raining outside with low pressure. How much should cranking compression vary?
I'm getting close to 110 psi on that calculator using 4.145" bore, 4" stroke, 6.2" rod, 9:1 compression, 600 feet altitude. I'm guessing on the intake valve closing. I'm using a cammotion solid roller intake lobe with 298 degrees duration at .020", installed at 116 intake centerline with 3 degrees advance, which I'm estimating puts my intake valve closing event at 82 degrees ABDC unless I'm doing my math wrong. Cranking compression on the engine currently is averaging 120 psi.If you use the link I posted how close are you to where it calculates? If your off a little I wouldn't worry, if you are off a mile do a leak down test.