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Discussion Starter #1
I just rebuilt the 390fe in my torino after it had about 80k miles on it. It was my first time doing a complete rebuild, but everything went smoothly. Engine started fine, cam break in went fine, and it drives great and strong and sounds good. Problem is that it smokes a lot through the valve covers, white smoke. Driving without the hood on the car, you can almost not notice it when cruising, but its obvious at idle, a guy even came up to my car at a stop sign to make me aware of it. Is this normal at all after a rebuild? I figured maybe it's all the grease I used burning off, but it doesn't look to be getting much better, although I only drove it maybe a mile or two. If any one has some ideas on this, I'd appreciate it. I figured I might try putting in some thicker oil, it has 10w-40 with some zinc additive right now. Also, theres no smoke through the exhaust.
 

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If it's been run for short periods of time quite a few times condensation can accumulate to the point where the oil shows milky. Hows the oil look?

Define rebuilt. It means different things to different people. Was it a running engine before? As in not overheated or froze?
 

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That indicates there is a leaking head gasket that is allowing coolant to enter the combustion chamber(s). Probably any of the center cylinders.

Retorque the head bolts. If that does not fix the problem, you will have to remove the heads and replace the head gaskets after you resurface the heads.
 

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I just rebuilt the 390fe in my torino after it had about 80k miles on it. It was my first time doing a complete rebuild, but everything went smoothly. Engine started fine, cam break in went fine, and it drives great and strong and sounds good. Problem is that it smokes a lot through the valve covers, white smoke. Driving without the hood on the car, you can almost not notice it when cruising, but its obvious at idle, a guy even came up to my car at a stop sign to make me aware of it. Is this normal at all after a rebuild? I figured maybe it's all the grease I used burning off, but it doesn't look to be getting much better, although I only drove it maybe a mile or two. If any one has some ideas on this, I'd appreciate it. I figured I might try putting in some thicker oil, it has 10w-40 with some zinc additive right now. Also, theres no smoke through the exhaust.
That indicates there is a leaking head gasket that is allowing coolant to enter the combustion chamber(s). Probably any of the center cylinders.

Retorque the head bolts. If that does not fix the problem, you will have to remove the heads and replace the head gaskets after you resurface the heads.
It's actually SMOKE and not STEAM? Also, is it coming from INSIDE the valve covers or is there just oil dripping onto exhaust? These FE's can be a bear to get all oil sealed up nicely at times, especially for a beginner.
 

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Discussion Starter #6
Does it have a PCV hose hooked up?
I had ran the engine before the rebuild without one, I just tried hooking one up and it swallows most of the smoke. Although I dont want it running back through the engine, I'll probably keep it hooked up for now to stop all the weird looks i get a stop lights
 

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Discussion Starter #7
If it's been run for short periods of time quite a few times condensation can accumulate to the point where the oil shows milky. Hows the oil look?

Define rebuilt. It means different things to different people. Was it a running engine before? As in not overheated or froze?
The car's a daily driver, so it doesnt have much of a chance to accumulate condensation, and the oil looks good. The rebuild consisted of new bearings for everything, new piston rings, new camshaft, and new stock cylinder heads
 

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Discussion Starter #8
That indicates there is a leaking head gasket that is allowing coolant to enter the combustion chamber(s). Probably any of the center cylinders.

Retorque the head bolts. If that does not fix the problem, you will have to remove the heads and replace the head gaskets after you resurface the heads.
I took extra care torquing the head bolts, stepping up the torque and moving from the center out. The engine cools just fine, so I doubt it's leaking coolant. I figured steam from the exhaust if it was. Though, I'll look into the radiator and watch the level after i drive.
 

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Discussion Starter #9
It's actually SMOKE and not STEAM? Also, is it coming from INSIDE the valve covers or is there just oil dripping onto exhaust? These FE's can be a bear to get all oil sealed up nicely at times, especially for a beginner.
It could be steam, though it looks thick enough to probably be smoke. It's definitely coming from inside the valve covers. It does suck getting oil sealed, though. It still leaks some from the rear main seal.
 

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It could be steam, though it looks thick enough to probably be smoke. It's definitely coming from inside the valve covers. It does suck getting oil sealed, though. It still leaks some from the rear main seal.
How far is your daily drive on this daily driver? If you have a 5 mile trip then daily driving it gives you a really strong opportunity for condensation build up.

If it were smoke, whitish smoke, it would be pretty irritating to your senses. If it doesn't smell like smoke, then it isn't. It sounds to me like you just need the PCV going and to take an nice 2 hour long drive somewhere.
 

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Discussion Starter #11
How far is your daily drive on this daily driver? If you have a 5 mile trip then daily driving it gives you a really strong opportunity for condensation build up.

If it were smoke, whitish smoke, it would be pretty irritating to your senses. If it doesn't smell like smoke, then it isn't. It sounds to me like you just need the PCV going and to take an nice 2 hour long drive somewhere.
I usually put 10-20 miles on it every day, but before the rebuild condensation never got any worse than making the valve breather seals a bit milky.
 

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I had ran the engine before the rebuild without one, I just tried hooking one up and it swallows most of the smoke. Although I dont want it running back through the engine, I'll probably keep it hooked up for now to stop all the weird looks i get a stop lights
If your PCV valve can't handle all the blow-by then the rebuild has failed. This engine needs a cylinder leak-down test to diagnose. Leak down testing requires an air compressor and a special apparatus that checks pressure drop across a 0.040" orifice while pressurizing a cylinder with air at 100 psi. The more air that is leaking past the rings or valves results in a higher drop on the second gauge. You can Google it. If the tester is not calibrated for 100 psi or only has one gauge or is without a regulator, then pass on it (I know that Harbor Freight has a cheapie that is BS).

I suspect your rings are not sealing well. Did you bore the block and replace the pistons - or just dingle ball hone the old cylinders? How much taper? What about removing the ridge at the top of the cylinders? A good used engine should certainly be less than 25% leak down on each cylinder. My 383 is 3-5% after 4 seasons on a Longacre leak down tester. The old engine I took out ran fine without excessive blow-by and was 20% when I sold it as a good used engine. Good luck. If you end up doing leak down testing yourself, watch the fingers when hooking up the air to the cylinder and all the time air is hooked up - engine can turn over suddenly and rapidly on air pressure, if piston is not right at TDC.
 

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Discussion Starter #13
If your PCV valve can't handle all the blow-by then the rebuild has failed. This engine needs a cylinder leak-down test to diagnose. Leak down testing requires an air compressor and a special apparatus that checks pressure drop across a 0.040" orifice while pressurizing a cylinder with air at 100 psi. The more air that is leaking past the rings or valves results in a higher drop on the second gauge. You can Google it. If the tester is not calibrated for 100 psi or only has one gauge or is without a regulator, then pass on it (I know that Harbor Freight has a cheapie that is BS).

I suspect your rings are not sealing well. Did you bore the block and replace the pistons - or just dingle ball hone the old cylinders? How much taper? What about removing the ridge at the top of the cylinders? A good used engine should certainly be less than 25% leak down on each cylinder. My 383 is 3-5% after 4 seasons on a Longacre leak down tester. The old engine I took out ran fine without excessive blow-by and was 20% when I sold it as a good used engine. Good luck. If you end up doing leak down testing yourself, watch the fingers when hooking up the air to the cylinder and all the time air is hooked up - engine can turn over suddenly and rapidly on air pressure, if piston is not right at TDC.
The PCV has been handling the smoke pretty well, there's none coming from the engine besides a very small amount of smoke from an exhaust leak. I probably can't afford the stuff for a leak down test, but I might do a compression check on the cylinders. I didn't bore the cylinders or replace the pistons. I couldnt tell any taper in the cylinders, there wasn't really a ridge, either, just some carbon build up. I've heard that sometimes the piston rings seal right away and sometimes they can take some miles. Are there any additives or things I can do to help the rings seat without another rebuild?
 

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The PCV has been handling the smoke pretty well, there's none coming from the engine besides a very small amount of smoke from an exhaust leak. I probably can't afford the stuff for a leak down test, but I might do a compression check on the cylinders. I didn't bore the cylinders or replace the pistons. I couldnt tell any taper in the cylinders, there wasn't really a ridge, either, just some carbon build up. I've heard that sometimes the piston rings seal right away and sometimes they can take some miles. Are there any additives or things I can do to help the rings seat without another rebuild?
If the PCV is handling the smoke, then it is doing it's job. Leave it hooked up and drive it. If it blows a bunch of oil or smoke out of the breather when you do heavy acceleration, that is when you have a problem.
 

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Discussion Starter #15
Yea, it doesn't puff anymore smoke under acceleration than it does at idle. With how well the engine runs now, I'll probably just see how it likes some more miles, which should happen pretty fast as I drive the car every day a fair bit. If it doesnt get any better though, I've heard that putting some bon ami down the carb works well
 

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If it doesnt get any better though, I've heard that putting some bon ami down the carb works well
Worst thing you could do is that, holy cow what a stupid idea...lets pour grit into a fresh engine.
"Let's pour some crushed rock down the carb" is just what you'd be doing, that is a main ingredient in scouring powders.
 

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Worst thing you could do is that, holy cow what a stupid idea...lets pour grit into a fresh engine.
"Let's pour some crushed rock down the carb" is just what you'd be doing, that is a main ingredient in scouring powders.
I have heard of guys using an abrasive powder in a drag racing situation, in the pits, where the rings weren't sealing in a cylinder immediately after new rings being installed.
However, as it was told to me, the powder was put into the spark plug hole, not the carburetor!
That being said, I'd agree with ericnova72, that it's generally a bad idea, unless you're an "old pro", and absolutely have to get those rings to seal immediately, to hopefully win a race...
 

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I didn't bore the cylinders or replace the pistons.
Did you even hone the cylinders?
If not, then they'll never seal.
Even if you did hone them, if the cylinders were not within limits, you'll be screwed.
My advice would be drive it, check the plugs to assess oil burn, and make a judgment call at that point.
It sounds like you'll need to consider this a "learning experience", since it was your first rebuild, and do another one using all the advice you can get (from people more qualified than me).
My other advice would be to always have a qualified machinist tell you whether the cylinders need to be bored, and to have the machine shop do the honing even if the cylinders don't require boring... unless you really enjoy disassembling your engine...
Piston wear can also be a problem (ring grooves, etc.), so if you aren't boring the cylinders, you should have a machine shop check the pistons when you have them hone the cylinders. If the pistons are too worn, then you may as well bore the cylinders regardless, since you'll be buying new pistons.

Best of Luck!
 

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How's the oil look? Should be clear. If it is milky, then water is getting in the oil and you don't want to drive it like that.
 

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White smoke

OK, here's the reason for white smoke. Black or dark smoke means no decision has been made. White smoke means they've elected a new Pope.
 
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