smoky engine...?

[SR20drftSX]

i got an 89 240 with the SOHC , 5 speed. 168,000 on the whole car and motor together. starts up and runs perfect...when i get on it in neutral it smokes quite bad...like up at around 4000-5000 rpm it smokes like a MOFO! , bluish whitish smoke , also when yu rev it with just the throttle body cable control there it some minor smoke comming from around the engine..its a darker thicker smoke tho...i just changed the oil and added some Restore with CSL and Bardahls No Smoke and Stop Leak oil conditioners...lemme know what you guys think and what should be done...hopin its nothin major..also how much is the typical rebuild(sohc)(for just new pistons and rings) and what is the typical price of a newish(70000-120000miles) DOHC engine?without the swap , just the motor...but thanks alot and any adivce is appreciated

Garrett , NY

SOHC -STOCK

[steve s14]

sounds like the motor is burning a lot of oil. have you checked to see how much oil it is actually burning, 1qt/1000 miles 2qt/1000miles?if it's using a lot of oil, you probably have bad valve stem seals or bad rings. since you are getting a lot of smoke during acceleration, it's probably poor sealing piston rings.if you are getting smoke from the engine bay, it's probably coming from the oil burning on the exhaust manifold or something else really hot from oil leaks. i would say probably from the valve cover.if it's not consuming large amounts of oil, a very rich running engine will cause black smoke and in extreme cases, white smoke similar to a blown headgasket.most likely causes for that would be a vacuum line broken on the fuel pressure regulator or a stuck closed fuel pressure regulator, a bad connection in the coolant temp sensor or a bad coolant temp sensor, a bad air flow meter and other things that can control the amount of fuel an engine gets.