84noname

it only does this when i first start it and usally if i drive for a while it wont do it again till it has sat for a bit

Damon

More than likely valve guide SEALS, although the guides themselves can also be worn.

84noname

thanks how hard are they to replace on a chev?

Apeiron

They're about the same as replacing them on any other engine. The process is the same.

84noname

thanks

84noname

bump

five7kid

iTrader: (14)

What else did you need to know?

84noname

is there anything else that makes the car smoke, could it be bad rings?

Sonix

iTrader: (1)

Yea, but if it only happens on start up, it's VERY LIKELY to be valve seals (or guides, if the engines got a LOT of miles on it).
Rings would smoke all the time when driving it. Hard acceleration would leave a nice blue cloud.

BlkLB9IROC

I have the same problem with the smoke on startup with my 87 tpi, I heard it was the valve seals. But they only seam to leak and smoke on startup and then they seem fine. This is very common i hear in older chevys

UNCLE TOM

iTrader: (1)

when changing valve seals i also like to put umbrella seals on all valves , intake and exhaust . they are cheap and can't hurt . you may be surprised at the sludge build-up when you remove valve covers . clean it up , lots of newspaper under car . make sure the drain holes at the front and rear of each cylinder head are not sludged up . this lets oil go back down to the pan after oiling the valves . i used a screwdriver and air press. on mine . then flush eng. and change oil & filter . hope this helps .

Apeiron

Positive seals are much better than umbrellas, and not much more expensive.

UNCLE TOM

iTrader: (1)

not sure what you meant with "positive seals" . i meant the seals in the keeper areas and the ones on the shaft of the valve . no big deal , maybe i am talking overkill . worked for me !!!

Apeiron

Umbrella seals are the thin little rubber domes that ride up and down the valve stem below the retainer to keep oil from dripping onto the valve guide. Positive seals are heavier rubber ones with a metal spring construction that are pressed onto the valve guide boss.

UNCLE TOM

iTrader: (1)

well we are both talking about the same thing . all seems good , i am , do not know about seals around the stem boss . sounds good , will check it out . do not want to argue . just telling what worked for me . more input is always a good thing . next time my valve covers are off i will check it out . thanks .

84noname

are the seals the same as the guides or differant?

Damon

They're different.

The guide is the metal tube/hole in the head that the valve stem fits inside to "guide" the valve on and off it's seat as it opens and closes. The seal is a mechanism (various types and styles exist) to prevent oil from getting directly onto the top of the guide up on the valve deck area inside the valve spring. If you get too much oil splashing up on top of the guide it goes straight down between the guide and the valve stem and then onto the back of the valve. When you fire up the motor the oil that leaked down the guide immediately gets swept into the combustion chamber by the incoming A/F mix. That's when you get the "puff" of bluish smoke on startup or when jumping on/off the throttle quickly.

The seals they used on mid/late 80s engines are "positive" style (plus the old o-ring & shedder arrangement on the retainer). It clamps onto the top of the valve guide and "squeegees" the oil off the valve stem as the valve opens and closes. Unfortunately, the rubber technology they had back then was not so great and these seals get very hard and brittle (although they may look just fine to your eye). Once they get hardened they can't do this "squeegee" function very well and the oil goes right past them and down the valve guide.

Earlier engines used just the o-ring and shedder arrangement, no positive seal.

Later engines (Vortecs, for instance) did away with the o-ring and shedder and went with JUST a posive seal, although the seals were much better since the technology was 10-15 years newer.

No factory SBC engine ever came with umbrella seals, although they are still popular for quick/cheap rebuilds becuase of their ease of installation and no need to do machine work to the head to use them. But they don't control the oil very well.

Also- if the valve guides are worn out it won't matter what seal you put on top. It'll still leak oil past the guides. But for 3rd gen Camaro heads if it's puffing blue smoke the most common reason is because the factory positive seals have become hard/brittle and aren't doing their job any more.