Compression Test Results Lower On One Side

[aroche25]

I did a compression test yesterday 90' NA, I did not oil the plugs and this was done at full temp.

Cly 1 175psi
Cly 3 179psi
Cly 5 180psi

Cly 2 160psi
Cly 4 166psi
Cly 6 168psi
Lower the compression across one side and the most in 1 and 2..
I know 183psi Is Perfect

Im doing a 120k Mile Timing Service, Rear Main and Upper Plenum Gasket replacement during winter break, because Im leaving for Gainesville for school this week and do not have the time right now.

What else should I do besides the maintenance mentioned to correct the compression issue?
Thanks In Advance.

[BigTDogg (MA)]

Do the timing belt properly and I don't forsee any issues. If you are sure it's done correctly (counting teeth between marks on cam sprockets), then you have an issue with the head on the DS

[stewartmotorsport]

The good news is that it does not look catastrophic. If your cylinders are all within 10% (and all of yours are except 1 that is off by 11%), you are probably OK.

Did you do a dry test AND a wet test?

That will tell you if the issue is rings or valves.

If compression stays the same with wet cylinders, then it's a valve / head / gasket issue. If compression increases with wet cylinders, then it's a ring issue.

Do a dry test first to set a base line. Then do a wet test and compare numbers.

[NolimitZ32]

At 16x I would bet its not your rings, when the rings go compression drops more, much more. As Tony said, redo the TB, if that doesn't fix it its either a warped/cracked (badly) head or more than likely a head gasket issue. Once again with that little of a loss I'd bet its the TB off by a tooth. Or maybe your nvcs sprocket is screwed up on one side messing with the valve timing.

[aroche25]

Something else to note I always hear a very slight miss on the side with lower compression.

[NolimitZ32]

Have you leakdown tested it?