Compression can be deceiving if your engine is using oil, becuase excessive oil on top of piston will tend to cause compression readings to rise, still can be the problem, but I would lean towards vlave guides and seals. Also, on your pcv system, even if the valve is new, if the breathing side (where the crankcase draws air off your throttle body) is stopped up, engine vacuum will pull oil right past your pcv valve and burn it off also. PCV system works like a loop, sucks through pcv valve and draws filtered air through your throttle body, which is filtered air. [8D]

 

Also please verify the color of the smoke. as mech259 stated in another post the fuel regulator can cause problems if it is leaking internally. This would be gas and as stated earlier gas is black.

 

I have found many engines with the age and mileage that yours has with bad valve guide seals. This does not mean your valves or guides are bad, just the seals. Replacing the seals is a relatively easy job and doesn't cost alot of money if you are set up to do it yourself. Bad seals allows oil to run down your valve guides and when your engine is started after sitting for awhile, this oil is burned and you get blue smoke until the oil is burned off.

 

Most Chevy's use an o ring seal around the valve stem for seals. We have, at my shop, used Ford umbrella seals in addition to the o ring seals, good quality rubber ones, not the plastic ones, to help deter oil consumption. The rubber ones are more flexible and allow a little more tolerance to valve guide wear. As SLJ stated, older engines will have some valve guide wear and replacing these seals is time consuming, but not impossible. It can be a full day job, but that is another story. Good Luck.[8D]

 

As has been said, your most likely issue is the valve guides +/or seals. The guide refers to the clearance between the metal hole & the valve stem, the seals are rubber and tend to harden & split. When the rubber seal is worn or gone, a little extra oil can weep down the guide into the intake runner & into the cylinder.(not alltogether bad) Not too unusual to get a puff upon innitial start up. If it is acting up on the road, either oil may be being pulled into intake runner through the guide (smoke @ idle & decel) or from the lifter galley into a bad intake gasket (smoke on decel after a hard run).


BTW smoke can be greatly reduced by using synthetic