Condition of 160k 2.8L?

[Canyonero]

I have a 1990 Isuzu Trooper with a GM 2.8L. The engine seems to run fine, I think I'm starting to hear a little clattering from worn lifters and it puffs a moderate bit of smoke when started (moreso on a semi-warm start, if it's been sitting for an hour or two). Doesn't seem to burn oil while running, and otherwise doesn't miss a beat It will stumble on acceleration when it's still warming up on a cold morning, but I think that's just because I have the air cleaner 'lid' flipped and it's missing the heat pipe from the exhaust manifold to pre-warm in intake air.

The engine has around 161k miles. I've taken good care of it, but I've only had it since 138k (five years ago, I don't put alot of miles on). What is the most likely cause of the smoke on startup? If I wanted to reuse this engine for some other application, could I get away with a head rebuild, new rockers,cam and associated bits (I have a spare cam from a 3.4L, would that work? :P), or am I looking at a full rebuild to make it a worthwhile effort?

[jackal2000]

probably needs the block honed, maybe bored and new piston rings.

[bszopi]

It could easily be ring blowby or valve stem leakby, both of which would most likely go away as the engine warms up and everything starts expanding.

I think you'd be fine with the small overhaul that you stated. And to topic jump, there shouldn't be any issues with running the 3.4SFI setup on the 2.8L bottom end. I have hardly any experience with the iron head engines, but it would be similar to doing a 3x00 top-end on a 3.1L...

[Canyonero]

Valve stem leakage is what I thought, but what do I know...

I've never torn down a car engine before, just worked on motorcycles and small engines. Part of me wants to do as little as I need to keep it working. Then again, I also have the urge tear it down completely. It's pretty much a worthless engine so I can make my stupid mistakes on it with no real harm done.