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#1
10-21-2009, 01:39 AM
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Re: 68 Z/28 Engine Smoking - Any Ideas?
Since the engine was just rebuilt, I would suspect piston rings. Blue smoke would indicate some oil blowing by the rings and out the exhaust. Sorry , that's probably not what you wanted to hear.
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 1970Camaro Z28 
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#2
10-21-2009, 02:25 AM
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Re: 68 Z/28 Engine Smoking - Any Ideas?
How was the break in done? Doesn't sound like the rings are seated... I hope it didn't break a ring... eeeek!
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~JAG~ NCRS#65120 68 GTO HO 4 spd Alpine Blue /Parchment 2 owner car #21783 71 Corvette LT1 45k miles Orig paint - Brandshatch Green - National Top Flight - last known 71 LT1 built. 71 Corvette LT1 42k miles Original paint - Black - black leather - only black LT1 known to exist. NUMEROUS Lemans blue Camaros, Monza Red and Daytona Yellow Corvettes & a Chevelle or two... Survivors, restored cars, & other photos https://picasaweb.google.com/lh/myphotos
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#3
10-21-2009, 03:34 AM
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Re: 68 Z/28 Engine Smoking - Any Ideas?
I would ask who did the rebuild and what type of piston rings were used, end gaps, piston to wall clearance, low tension oil rings or standard? Did they install valve stem seals when the heads were rebuilt, were the valve guides replaced, new valves, etc. How were the cylinder walls honed, what grit, on what type of machine?
Paul
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70 Camaro LA Z-28 03B Citrus Green LT-1 M-40 3.73's 69 Camaro X-77 Z-28 10C Cortez Silver M-21 3.73's Deluxe Project X - SOLD 69 Camaro X-77 Z-28 01B Garnet Red w/Black top, M-20 3.73 Deluxe Houndstooth
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#4
10-21-2009, 03:47 AM
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Re: 68 Z/28 Engine Smoking - Any Ideas?
Thanks for the suggestions guys. The engine was done around 5 years ago so I doubt the engine builder will remember exactly what he did. I do know it was new valves. I'll check to see if valve stem seals were installed, but I expect so. I've been dreading rings as the problem....definately not what I wanted to hear to be sure. If it broke a ring, wouldn't there be other issues (noise, debris in the oil pan, etc)? If the rings aren't seated, is there any way to do this now without ripping the engine apart? I'm not a complete novice, but I confess I have no idea what the difference is between low tension oil rings and standard oil rings. Thanks again for the suggestions.
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#7
10-21-2009, 08:04 PM
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Re: 68 Z/28 Engine Smoking - Any Ideas?
If the motor runs well when started then starts puffing blue smoke after it heats up I would suspect the seals or the intake. Pull the dipstick smell it and look at the color of the oil. If the rings are not seating properly they will allow some of the combustion mixture into the oil pan and you should be able to smell it.
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#8
10-21-2009, 08:36 PM
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Re: 68 Z/28 Engine Smoking - Any Ideas?
[ QUOTE ]
Check out the condition of the plugs..might be just be a valve stem seal....just a thought [/ QUOTE ]Do what Joe suggests. If the heads did not get the good seals (Perfect Circle) etc, the little O ring seals are probably brittle. The valve guides could also be worn if they were not replaced on the rebuild. Not sure I would spend the money or take a chance on an original block to have all 8 cylinders sleeved just to have/retain the original pistons. JMO 
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