I've been dismantling my stock TPI engine for a while now and I still can't figure out what's causing the car to puff a huge blue cloud of smoke when I start it up. It also consumes lots of oil and puffs here and there while driving as well.
The valve guide seals are in 10/10 condition, I guess the previous owner had them replaced as an effort to fix this problem.
The valves need lapping, though, and all the ports have rusty goo inside.

I have two questions:

1. Is this clearly a sign of bad piston rings? Here's a pic of my dirty cylinders if it helps at all:
http://aijaa.com/img/b/00376/13036703.jpg

2. If I am to replace the piston rings, can I do it without removing the motor from the car?
Can I just remove the oil pan from underneath the car and do it that way without any major problems?

 

How loose are the valves in there guides ? The pistons dont look real washed off like poor ring tension/ blowbye a leak down before you pulled it down/compression test should have been preformed.

 

had that issue, i replaced my valve seals and that helped a good deal. It smokes a bit while driving, but i think thats cuz after 178,000 miles, the rings have gone bad.

puffs of blue smoke on startup are attributed to oil leaking past the valves and into the cylinder while its parked, if you rev the motor and you see signs of burning oil (blue or sometimes black smoke) that is a good indication of bad rings.

 

The valve guides were my first thought as well. I had the same problem on my 305TPI, but lucky for me, the main bearings spun so I don't have to fix the blue smoke anymore.

 

Check oil return ports toward the ends (front and rear)of the heads if they are stopped up that will cause it to smoke also. Leaves to much oil on top of heads and it will leak past the valve guide seals.

 

Valve stem seals...pretty sure Chevrolet has a part number for the smoke

 

Isn't the rule of thumb that excessive white smoke on a warm day during startup was valves, and blue was rings?

 

always been told that white is just condensation, blue is oil, and black is rings. been explained that way to me atleast.

 

Oil smoke is oil smoke no matter where it enters the cylinder.Usually blue,can be black if really bad.Black is usually fuel related.Smoke on startup is usually due to bad seals/guides,or,as mention above,slow oil drainback.Another often overlooked source of oil entering the cylinder is a bad intake gasket.A worn cam lobe can also pull oil into the cylinder.W/O doing a compression test followed by a leakdown,it's pretty hard to determine exactly what the problem may be unless something really obvious shows itself.The 1st step to diagnosing it is to pull the plugs & looking @ them. @ the very least,you can usually tell which cylinders are effected & be easier to pinpoint the problem.