Cylinder Compression results

[mboston]

Picked up a z about a year ago and have been working on it. Engine was rebuilt when I got it but felt lacking these past few months. Did a compression test I get.

140 119

130 121

136 120

Front

When the engine was rebuilt, all the seals and gaskets where changed and heads resurfaced. My only guess it the piston heads are bad? Any thoughts, Thanks.

[NolimitZ32]

Piston heads?

Compression results like this suggest that the head gasket on the Driver Side (USDM) was not torqued or machined properly. The general consensus is if you have less than 10% difference between adjacent cylinders then you are in the clear. Your results aren't that bad but they aren't great either. Are you having any fluids intermixing or excessive backfires, or overheating issues? If not then I would say you are ok. If you are really worried about it then do a cylinder leak down and carbon monoxide block tests.