Just wondering what the compression should be on an 89 Bonneville. I pulled out the front 3 plugs and tried a compression test. The stupid gauge wasn't working very well. It was one of those gauges that you hold in the spark plug hole. Anyways I know I should get one that screws in. But what should the compression read on these cars? I was only getting around 110-120.

Given the inaccuracy of the shove in type (good guages screw in and seal with an o-ring.), anything over 100 psi on cranking is probably OK. What I look for more is about the same reading on all cyl.