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Old 07-07-2004, 12:28 AM
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Oil smoke or....? 383 Chevy

Some time ago I asked this board about sudden oil pressure loss on a 383 Chevy. I received many educated quesses as for the reason, and tried to take all of them into account when assembling the engine again. The engine is now back together, and here is the combination:

* '72 350 block (2-bolt)
* Eagle cast crank (3.750 stroke, 350 mains)
* 6.000" Summit H-beam rods
* KB Silvolite pistons
* Total Seal Gapless (2nd ring) rings
* Comp Cams mechanical roller, small base circle
* TFS 195 cc aluminum heads, 67 cc chambers (milled from 72 cc)
* Performer RPM Air-Gap intake, Quick Fuel "Holley" 750 cfm
* All MSD ignition
* Various other stuff (full roller timing chain, headers, aluminum water pump, Melling M55HV oil pump (high volume, std pressure) etc. etc.)

When I start the car, a puff of oily smoke comes from the tailpipes. The valve stem seals seem to let some oil through, even though they have only about 100 miles on them. But that's not my main concern. When I warm up the car, stop and let it idle for a while, some grey-white smoke starts creeping up from the tailpipes. A small amount at first, then more and more. It's not smoking like a chimney, but you can definetely see it's smoking. If you hop in the car and drive, it doesn't seem to smoke excessively (i.e. no smoke in the rear view mirror). But when you stop and let idle idle for a few minutes, there it comes again.

The smoke is sort of grey-white, not blue. It doesn't smell like coolant, but it doesn't really smell like oil either. The oil pressure is good, ~32 psi on idle when warm, ~44 psi @ 3200 rpm. The car is not overheating, even when running at idle for extended times. I ran the car with the radiator cap (Moroso 22 lbs) off, and the water was circulating very well, and the radiator did not puke when revving.

I haven't done a compression test and/or a leakdown test yet. I checked the vacuum modulator on the trans, and there did not seem to be any oil in the hose. I pulled a couple of spark plugs (Denso Iridium) and they were quite black and seemed to have oily residue in them.

Any ideas? Rings not seated yet? The rings have less than 100 miles on them, like the rest of the engine. The rings were taken off the pistons after the oil pressure loss happened (I changed the rods from I-beams to H-beams) but they were put in the same pistons and cylinders again.

Something else? Should I just drive it and see what happens?

Sorry again for the long post, but I wanted to give all the info I had (and probably forgot something anyway).

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Last edited by Finmike; 07-07-2004 at 01:42 AM.
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Old 07-07-2004, 02:07 AM
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are you sure your getting the proper air and fuel mixture? check that out im not really too sure because im not a pro or anything like that but it sounds like your mixture is not right. but thats just an educated guess.
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Old 07-07-2004, 11:43 AM
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Fuel is black.




I'd blame coolant loss through the head bolts or head gaskets first. If tou are sure about the gasket's, I wouldn't worry much about it till you get some miles to seat rings and such. Have you checked for condensation in the mufflers?
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Old 07-07-2004, 12:33 PM
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Just to be sure that it isn't a head gasket problem this is what I would do...
Go to your local I/M station (assuming that you have one) and ask them if they can check your radiator for Hydrocarbons. To do this you simply get the car warmed up and remove the rad cap and put the probe next to the opening and watch the readings. If you have any reading at all then you have a combustion leak.

OOPS...I failed to notice that you live in Finland. There must be some kind of an exhaust probe that you can use that can detect hydrocarbons. Well I hope that I at least gave you somewhere to look.
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Old 07-07-2004, 04:32 PM
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^^ they make $20 kits that do the same thing, you hook em up to a vacume prot and your rad and if the mixture turns colors u have a leak.
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Old 07-08-2004, 12:12 AM
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Thanks everyone for your suggestions. Here's some more info:

The head gaskets are new Fel Pro 1003's. The head bolts are ARP's. There seems to be no loss of coolant, however I discovered yesterday that the oil level on the dipstick was down maybe half a pint from what it was when I filled the oil (and marked the dipstick with the correct level). So that kind of directs me to oil being burned, however it is not clear whether it's from valve stem seals or rings.

A friend of mine has a garage with an exhaust analyzer that's used for smog testing around here. It can be also used to detect any signs of exhaust gases in the coolant, so I will call him and see when I could drive by his place, just to be sure.

Thanks again for everyone.
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Old 07-08-2004, 08:30 AM
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Here are a few things to look at.

Are you running a PCV valve? Check the hose coming from it to the carb for oil in the hose. If there is oil, you need to install a baffle below the PCV valve.

You could have an internal vacuum leak where the intake bolts to the heads in the valley area. This will suck oil into the cylinders also. The only way to check this is to remove the intake and visually check the intake gaskets.

I personally think the rings are not seated yet. Check the obvious (PCV valve and hose) and drive it. If it is the rings the "symptons" will go away eventually. May take as much as 1500 miles.
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Old 07-08-2004, 11:17 AM
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When I put my engine back together again after a camshaft exchange some time ago I had the same problem, it showed up during running in, -blueish from drivers side pipe.

Since I had reinstalled the pistons and the old rings I took it for a spin, loading the engine good in 3rd (th400), coasting, loading it again, in some different cycles.

The theory is to load the rings to settle properly, coasting does the opposite, allowing oil to clean out the rings, loading it again etc....

After that the smoke was gone.....

It will probably dissapear with ring settlement, as already mentionend

You decide how long it will take....
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Old 07-08-2004, 06:25 PM
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Break in

[color=yellow]Doc Here

Try just driving it at Various Speeds / Loads For about 1000 or 1500 miles, and aviod prolonged driving at Constant speeds.

If it's break in it will clear in that time.

If you want, just block the PCV Vacuum hose While you drive it during that time, it will eliminate that possibility too.

Regards,
Doc
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