I just purchased an exceptionally clean 1983 280 ZX here in AZ with just under 300K miles on it. The first thing I did was a compression test which showed 125-129 lbs in all cylinders. I believe turbo compression is typically lower than a NA engine. My question is does this reading mean the engine is in very good condition or is there significant wear (albeit even wear)?

The car is not yet streetable as the clutch needs to be replaced. The turbo spools but the engine does not seem to rev much above 4000 RPM (have been told it's a mass air flow sensor issue).

 

that's a little wear as factory compression is supposed to be 140psi. I'd say though your engine sounds like it's in good shape. The other thing you could check would be just to see if the reading goes up if you add a drop of oil, or you might actually have a compression tester that's kinda off. My compression tester was a cheapo one, and overtime it kept showing lower readings, but would always show the same across the board. Tried another better brand tester and my compression was at factory.

 

Welcome to ZDriver and also welcome to owning a 280zx turbo!

#1... Buy a 280zx Haynes manual. All basic & advanced info (including compression specs) is laid out in that book.

#2... Do a basic tune up (NGK spark plugs, new wires, cap, rotor), and check all sensor connections for corrosion. If there are still problems, it will then be easier to diagnose.

#3... The 280zx's actually use an AFM (Air Flow Meter) rather than MAF (Mass Air Flow) sensor.

 

A leak down test will give you a better idea of what condition your rings are in. From the sounds of the compression test, the motor is still relatively healthy.