Did a compression check on my motor today. Its a 350 bored .040 with 67cc chambers. All the cylinders were in between 70 and 80 psi. My chiltons is telling me it should be 150 psi. I have some oily plugs so I decided to do the test. Expected to find a couple cylinders low. But seening how there all within 10 psi of each other I'm at a loss. The engine was rebuilt 3 years ago.