Well I have a 383 LT1, with a big solid roller cam, and some great flowing heads. Thing runs like hell, but it smokes. Has smoked since almost day one I bought the motor. Builder says nitrous rings, for a 200 shot, will smoke, but I dont buy it. They would smoke a little, but this smoke i'm seeing almost leads me to believe heads. The longer it sits, the rougher the startup. Burns alot of smoke maybe even fouls plugs. Once its hot and cleared up, runs great, no smoke normally. WOT under heavy load it will start puffing smoke again. I dont know which way to go. I dont know when these heads were last rebuilt, bought motor used, however it had just had fresh rings and bearings to my understanding. Assuming if it were rings it would smoke ONLY when cold, or ALL the time. Any ideas? Wife is pregnant, and busy with work or id LOVE to pull the motor out and clean up my engine bay like i've been wanting. This is a hot car and spent alot of money to build it right, just a little frustrated now. Anyone have any words of wisdom?

 

PCV system problem?

Bad hone job

Bad tune leading to glazed cylinders and rings that won't seal, or other direction and scored cylinder walls due to lean, detonation.

Either way something is wrong, it won't smoke just because the rings were gapped for nitrous.

Intake manifold leaks are typically high vacuum conditions, which is not when you say it smokes.

Leak down test?

 

words of wisdom..

if you paid someone to build that motor, take it back

in addition to what has already been stated it could also be rocker studs not sealed, broken valve guides or leaking guide seals

 

FWIW, my rings are gapped for a 200shot of nitrous and I have no smoke. Are we talking black clouds of smoke? If that's the case, im going to guess the rings were not properly gapped (maybe gapped for 500shot ) or the motor was not broken in/had the rings seated efficiently. At least you didn't build it yourself and someone else may be responsible for fixing it Hopefully that's not the case though, and before jumping to conclusions, I would check the pcv system, tune, inspect the heads, and leakdown test like the two previous posters suggested. Good luck man

 

Just a shot in the dark here but what kind of fuel pressure are you running? I'm with the other guys, noway should that engine be smoking just because the rings are gapped for nitrous.....

 

381 (500HP) plus a 300-shot, and the engine doesn't "smoke". And never has in the 10 years since it was built.

 

Find which plugs are fouled and do a leak down test on those cylinders

 

Oil on the plugs, maybe very bad valve stem seals?

 

Well I finally have gotten serious and started digging into my problem. I pulled off my valve covers, and im going to run my valve clearances... as it needs done sometimes. But I decided to start pulling plugs... and each of them all looked very similar...burnt oil coated. Now since I can't pinpoint a cylinder im going to say i'm picking up oil somewhere in my intake. So I popped off the TB, and the butterflies were coated in burnt oil residue. So I look inside the intake and there is QUITE a bit of oil residue also! Now this is leading me to believe somewhere my intake is sucking oil! So, I am going to replace my PCV valve today, because I have NO IDEA how old it is, or which motor it even came from. My 2nd option im doing is going to replace the valve cover breather hose, to an actual breather. My guess could be it smokes most when the motor is cold, because there is more crankcase pressure when cold, or high load? Sound like its possible? Its my best bet so far. If valve guide seals or stems, or even bad rings were causing this I wouldnt believe I would see so much oil where I am. That, or I have heard of intake leaks around the gasket? I'm getting somewhere here! To answer the questions, when the motor first started it DID have high fuel pressure... however I corrected it right away. The story on the motor, came out of 1995 corvette. Guy built it for the vette spent big bucks. Got the computer with the tune for the motor already in it. The motor was just freshened up, rings and bearings, that winter. The vette guy decided he wanted to go LS and through the buddy of mine who was doing the install I picked up the motor. For the price I paid I came out smiling. Anyway, the tune was for the motor, and FP was good, break-in was good. I also took the car to Speed Inc on the dyno last year, here is the video you can see the smoke http://www.youtube.com/user/speedrac.../1/bfkDjZLNkRk Besides that I think everything is on point. I never got an exact date of the last time the heads were gone through, but im assuming the winter also. Motor was spraying 200 shot at the strip when it was in the vette, and rebuilt every winter for the 3 years this setup has been together. Thanks for helping

 

A little bit of backflow through the vent line from the valve cover to the top of the throttle body isn't unusual. But yours sounds excessive. Adding a breather will eliminate the oil flow into the intake, but the question is - why is there so much blowby in the crankcase that it is pouring out of valve cover, rather than through the PCV valve?

There shouldn't be any pressure in the crankcase - hot or cold. The PCV valve is there to hold it under vacuum.

If you washed down the cylinder walls with fuel on a brand new engine, it might explain things.

 

That's ring smoke at WOT from what I can see in the video.