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Light smoke in valve cover

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Light smoke in valve cover

Posted: 9/11/10 9:26amMessage 1 of 7
o
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Rocklin, CA - USA
Joined: 4/2/2005
Posts: 484
Vette(s): 1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.

I took my PVC valve out of the passenger side valve cover and notice it smoke slightly out of the valve cover. Is this normal could this have anything to do with the car not holding idle at high engine temps?

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Light smoke in valve cover

Posted: 9/11/10 4:19pmMessage 2 of 7
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HOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
Look more like smoke or steam?

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Light smoke in valve cover

Posted: 9/11/10 7:30pmMessage 3 of 7
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Rocklin, CA - USA
Joined: 4/2/2005
Posts: 484
Vette(s): 1970 T-Top350/350hp numbers matching 4 speed. It's a mess and 1970 Convertible 4 speed.
It looks like smoke
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Light smoke in valve cover

Posted: 9/11/10 8:13pmMessage 4 of 7
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Oak Creek, WI - USA
Joined: 5/21/2008
Posts: 2041
Vette(s): 1981 Great White Shark. Red Interior, 350/190 hp. PS, PB (SS), A/C CC, T-Tops. Served three years in Active Duty Army, then Retired Air Force after 34 years! Badger State Vettes Car Club. 175,000 Original miles!! Now own a 1998 C-5!
I do not think this has anything to do with the idle of the car!!  Smoke in the valve cover??  Could it be just "hot" oil?Ermm
Dan
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Light smoke in valve cover

Posted: 9/11/10 8:36pmMessage 5 of 7
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York, PA - USA
Joined: 5/18/2010
Posts: 1518
Vette(s): 1969 daytona conv. all original 350 350 380 4 sp w/air..and hard top
Smoke coming out of the PCV is just blow by..unburned gas still in the engine..the PCV sucks that has out of the crank case and burns it in the engine..the valve needs to rattle when you take it out..if there is any question that it is bad replace it..check the hose right at the base of the carb..it could be torn. If it is really hard replace it..use a good hose clamp also..all (for the PCV)..if you get a ton of smoke coming out of the PCV hole you may also have worn rings..a wet compression test will tell you that..probably not a big deal..WITH a fire extinguisher next to you..spray carb cleaner around the base of the carrb..if the idle changes the carb or gaskets are leaking..setting the timing and idle mixture and idle speed is an art..they all affect each other..if you turn the idle screws all the way in and the car doesn't change idle the carb needs rebuilt or the primary needles are not in right..LMK.
Rich

My first parade at Carlisle 2010
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Light smoke in valve cover

Posted: 9/12/10 7:59amMessage 6 of 7
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HOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
Also, check the PCV valve itself and the breather going into the other valve cover. Basic tune up stuff that will prevent the engine from breathing well if neglected over the years...

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Light smoke in valve cover

Posted: 9/13/10 8:34amMessage 7 of 7
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1034
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
You are describing blow-by.  It is normal for an older engine.  As the rings wear a little, they leak a tiny bit of compression into the crankcase.  Since your crankcase is full of splashing oil and vapor, adding hot compression gasses burns a very small amount of that vapor and blows it out any opening.  Rich is is correct that the PCV normally sucks it out so you don't notice it.  Unless there is a column of smoke, don't worry about it.

Larry
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