68 Z/28 Engine Smoking - Any Ideas?

[68 RS Z/28]

I kind of thought that boring it out and going with oversize pistons would hurt the value - wouldn't really be a 302 anymore, that kind of thing. Anyway, I'll try replacing the valve stem seals and see if that helps. Thanks for the help!

[Salvatore]

Why would you think that it was not a real 302 being 30 over??? Who would really care about that? I get nervous when people talk sleeves for no reason IMO but that is just me. If you look at it by not being original because it would be bored.....its not original anyhow because of the sleeved motor. Hopefully a sleeve is not moving around in the bore. Try the umbrella seals. They don't need to have the head cut. But they do move up and down with the valve because they are not fixed to the head. Should be better than nothing though. Good luck!

[SuperNovaSS]

Why not try a leak down test before chasing a ghost? It will give you a lot better idea of what is/is not going on. Didn't you say only one guy referrenced blue smoke? Is the engine using any oil?


Jason


Jason

[GreenLS6]

I'd do a compression test first-check balance between cylinders.Look for something obvious. Then a leakdown.
O-ring seals SUCK. Machine for teflon seals or at least get the good rubber sleeve seals(they stay put and last longer) Depends on the valve springs you have though(Internal diameter) If it's only smoking when you stop then check the needle and seat or spray carb cleaner around the intake gaskets. You have higher vacuum at idle a may suck oil from a warped intake . Although a MO doesn't have much vacuum anyways. But it sounds good doin it!!
Good luck

[njsteve]

On the warped intake idea, you can also have a leak on the underside of the intake that sucks oil from the lifter valley into the intake runners without ever giving any indication of a vacuum leak on the outside of the intake.

My vote is for the dried out rubber o-ring valve seals. After sitting a long time, those things can just fall apart on their own. They would also give an inconsistant oil down that would occur randomly and not all the time, depending on oil flow/engine rpm.