LT1 Smoking bad on Acceleration
Thread Starter
Staging Lane
Joined: Mar 2016
Posts: 58
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LT1 Smoking bad on Acceleration Hi I have a 94 LT1 in my 67 Camaro. Simple stuff cam , roller rockers, electric water pump etc. car was smoking a ton so recently I did head gasket, intake gasket, rear main, piston rings, injectors, plugs. Seemed to help a lot with the smoke but it still smokes bad on hard acceleration. Also seems to be running weak. I think it's misfiring but the smoke seems like oil to me. Valve seals? I heard valve seals only really smoke on startup so I don't know. Any help greatly appreciated
On The Tree
Joined: Feb 2022
Posts: 196
Likes: 72
From: Grand Rapids, MI
Smoking while accelerating is generally accepted as bad piston rings. In my experience bad valve seals will show themselves once the engine has warmed up, been turned off for several minutes, allowing the oil to get into the combustion palace, and then the engine is fired back up again burning all the leaked oil.
If your valve seals are excessively worn when the engine is on its intake stroke the oil will be sucked into the combustion chambers and you'll have a choo choo on your hands. I cannot believe you didn't have the cylinder heads gone through, at the very least new valve stem seals installed before putting it all back together to rule those out. If you are getting oil into the combustion chambers it will show up on the spark plugs and from there you can determine what cylinder or cylinders are giving you the problem. If its burning oil the smoke will be blue.
Thread Starter
Staging Lane
Joined: Mar 2016
Posts: 58
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I have the valve seals just wanted to figure out which issue it was exactly and ive seen some methods for doing it while the head is on. Not sure how that would go. If I have to pull the heads again not the end of the world. Also just pulled all my injectors to see if any were leaking like they were before. Everything looked good. But spraying water on each header pipe revealed I have a whole 3 cylinders not firing... from what I can see every cylinder has spark and fuel. Pretty weird. Also oil leaking from my left pipe. Don't think that really helps figure out the culprit though.
My ponit is that if you really are burning oil that's getting into the combustion chamber you will see evidence of this on the spark plugs. There will be cooked on oil which eventually causes them to foul and if you notice this on any of your plugs then that's cylinder that has an issue. It could be due to worn out valve seals, excessive guide wear or cylinder rings. A compression and leak down will tell you what your problem is. Low compression that gets better after oil is injected into the spark plug hole is pretty good sign of a ring issue just as a cylinder leakdown that loses air pressure too quickly. If you can hear air hissing through the throttle body then you have air getting around the intake valve seal which is not good just as hearing air coming out of the exhaust pipe means you have a bad exhaust valve seal.
Thread Starter
Staging Lane
Joined: Mar 2016
Posts: 58
Likes: 1
Any ideas on the 3 cylinders not firing even though they have fuel and spark? I will check plugs and do a compression/leak down test in the meantime. I have a new msd distributor sitting but I mean all cylinders have spark. No wonder it runs/sounds like sh-t
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Verdad Gallardo If you have bad valve seals, usually there’s a bigger problem going on like worn valve guides, which means valves are not seating properly. A leakdown will have you for sure certain if there is compression escaping and how.
A simple way to check for worn valve guides is to take your two thumbs and press against the valve spring to see if there's excessive movement. Movement should be minimal.
Thread Starter
Staging Lane
Joined: Mar 2016
Posts: 58
Likes: 1
Gotcha I'll pull the valve covers and see how much movement they have. Pulled all the plugs and who would have guessed, all 3 non firing cylinders have oil caked up on them. Also did a compression test. 160-180 on all of them. Not too sure how to properly do a leakdown have to do some reading. Just put air to it at TDC I would imagine
Thread Starter
Staging Lane
Joined: Mar 2016
Posts: 58
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Wow just did distributor, plug wires, plugs, and pcv valve and man what a difference that made. Never drove an old v8 car like this before and I had a strong feeling she wasn't even close to her full potential boy was I right. Pulled out and spun through 4th like nobody's business. Then got pulled over for the car smoking like a freight train. Going to mess with these valves tonight.
Thread Starter
Staging Lane
Joined: Mar 2016
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Popped the left side valve cover off. Spun the motor so the rockers were loose and tried wiggling the valves. None of them budged even a little bit. Still going to do seals but I can't help but think how hard it would be for that much oil to get through a tight valve guide regardless of the seals condition. What could it be after rings, head gasket, valve seals, pcv, etc. only other thing I could think is the cylinders out of round.
The piston rings will follow the bores as the piston travels up and down in the bore to keep the seal and valve stem seals can still cause an issue even though your valve guide clearance is good. I'm not so sure you have a valve stem seal issue and you said your compression was good accross the board on all the cylinders, even those where you have oil fouled spark plugs. I'm afraid your issue could still be the rings and I'd do a cylinder leak down test to figure out just exactly what the issue is. Cross your fingers that it is valve stem seals.
Popped the left side valve cover off. Spun the motor so the rockers were loose and tried wiggling the valves. None of them budged even a little bit. Still going to do seals but I can't help but think how hard it would be for that much oil to get through a tight valve guide regardless of the seals condition. What could it be after rings, head gasket, valve seals, pcv, etc. only other thing I could think is the cylinders out of round.
Last edited by SS RRR; May 10, 2022 at 05:08 PM.
Thread Starter
Staging Lane
Joined: Mar 2016
Posts: 58
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So I just finished the valve seals. One was popped off not sure if I yanked it off pulling the spring or not. Still smoking the same it seems maybe a little better. Pretty out of ideas. I guess the only thing it could be is messed up cylinders?
You can somewhat tell what's going on by doing a compression test and if there is a suspected cylinder(s), spritz a little oil into the cylinder and do it again. If compression does not jump then most likely you still have compression leaking through the valves, if compression does jump then you may have issues with piston and/or rings. If you do a leakdown you can pinpoint exactly where compression is leaking out.
Thread Starter
Staging Lane
Joined: Mar 2016
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Still haven't figure it out. Started tearing down to send to a machine shop and noticed something interesting. Pulled the headers and the rear 2 cylinders are wet with oil the rest look fine. Any guesses? One thing I'm thinking now is there's a hole at the back of the intake that clearly has oil pressure as i remember it spraying all over when I first had the motor back together. I have a small bolt in there to plug it but not really sure what it's for. Could that be feeding oil into my intake say if the bolt is too short? Just a guess