I'll post here as most users here have reasonable (trusty) answers, or suggest a good forum.
A friends 1986 PU failed the Cal visual smog due to high/excessive tail pipe blue smoke, it passed the general HC, and CO test, but failed the visual of the tail pipe. We did compression test 175psi +/- 5psi on all 4 cylinders.
I suspect leaky valve stem seals, at 250Kmiles, but the spark plugs look decent. The design of this engine requires to change the headgasket as the rockers bolts are also the head bolts, some forum users have succeeded in avoiding the headgasket replacement, but it seems risky.
Here are the spark plugs as pulled out on the right side and after cleaning them on the left... we should have replaced them, but this is remote sierras location... the nearest town is 40 miles away!
ToyPlugRemovedJan24.jpg
thank you and Happy New Year
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