[82 vette]

My 67 Chevelle 396 is smoking blue out the pipes and is also blowing oil out the breather on the valve cover. I have had this car since 1978 and am planning a restoration anyway but am curious what is causing this. You can drive for about a mile with no smoke then suddenly it will smoke bad and really rolls out when you back off the gas while car is still moving. I feel it is building compression in the crank case. The car has always ran great and still starts good. Would worn rings cause this or could it be something else.

[ssmonty]

IMHO it could be bad rings, worn valve guides, worn valve guide seals, too much oil in pan, or any combination. The delay could be the time it takes for the oil to get hot enough to get slung onto the cylinders by the crank, or run down the valve stems. Do you see a blue puff of smoke when you stop, wait 15 minutes and restart?(valve guide seals) You need to do a compression check. Blowby out the valve cover breather is a sign the rings are worn. Same thing applies to smoking out the exhaust on deceleration. You might try a can of "Engine Restore". It helped me years ago. Good stuff for older engines! What do the plugs look like?
If this just started happening you might try swapping out the PCV valve.
Also check the vacuum for a possible intake gasket leak.
How many miles? After 30 plus years(another 10 before you got it) I don't believe I would be prognostic to say that it might be time for an overhaul.
ssmonty