I was planning on doing a compression test and was wondering what the PSI should be with a .30 over bore on a 4.6 4v motor.
i assume wit hte bore the compression #'s should be higher
Boring over won't significantly effect your compression test numbers. Also, the main thing you want to look for in a compression check is even compression. All the cylinders should be within 10% of each other. If they aren't, this can indicate a problem.
The actual number that you get in a compression test is not that useful because it is affected by too many parameters. The main ones are compression ratio and cam timing (especially the intake valve closing point). The numbers are even affected by altitude, which makes it impossible to compare engines. So just make sure the compression is even across all the cylinders. A leak down test can provide further information about the health of your engine and can be more effective sometimes.