So I've got almost the same problem I think. Got an 84 12a. started up 1st try. Then after running for 30 sec starts PUKING thick white smoke. The owner said it ran fine in the spring. When I got it the coolant tank was dry (well about 1/2 inch of green slime...) So I've cleaned the whole system out and filled it back up. fresh gas and all the little things i could think of. No bubbles or foamy oil. I don't have a place to work on the car yet. does this sounds like rings as well? If so can I drive it down the street to work on it. Or will that just make it worse.

 

Almost the same problem as what. Your paragraph is missing part of your train of thought. If it has a blown coolant seal, you could drive it for a short distance, as long as you don't overheat it. Sometimes a blown coolant seal will steam clean the inside of the engine, make teardown and parts cleaning very easy.