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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: Chuck Step-a-side on September 28, 2017, 06:10:36 pm
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I have an 1984 Silverado Stepside with a center-bolt 350, Edlebrock 4 bbl. married to a surpetine belt drive. I have just finished replacing my blown head gaskets along with installing new Edlebrock manifold, new headers, exhaust pipes and Super 44 mufflers. The truck runs good with a couple of minor issues.
The idle is kinda rough and this could be because I've set all the rockers at a half a turn after zero lash. I don't have any vacuum leaks and adjusted the carburetor as recommended by Edlebrock. The spark wire and plugs are new and gapped at .045". I have the timing set at 8° and idle at 650 rpm in drive. It's 900 rpm in park.
The other issue is there seems to more smoke than usual coming out of the breather cap. I know I can run a pipe from the breather to the air cleaner lid, but is there any other way to reduce the smoke? I have checked the pcv valve and it good. I'm open for any suggestions. Thank you, Chuck
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You have vacuum at the pcv valve? If it is pushing smoke out of the breather with it running despite the pcv system working it sounds like you have blowby. Also how did you determine zero lash when you made your adjustment? Did you follow the sequence or the firing order?
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I followed the sequence - cylinder 1 at power stoke and adjust 6 rockers with no up and down rocker motion. Explain the blowby issue for me. Thank you, Chuck
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Blowby his a excessive about of oil by the rings . I replaced my pcv onetime but soon found out the hose was clogged to so check your line also.
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Blowby occurs when an effective seal between the piston rings, pistons and cylinder walls becomes overwhelmed or otherwise fails, allowing an above normal volume of combustion gasses to leak past or "blow by" the piston rings into the crankcase, thereby pressurizing the crankcase. Although, the primary purpose of the rings is to seal the combustion chambers around the interface between the pistons and cylinder walls, some leakage past the rings is unavoidable since moving parts require relative clearance to function without seizing. Even when new, piston rings cannot provide a perfect seal between the pistons and the cylinder walls, so allow a "controlled" amount of combustion gasses to enter the crankcase. Normally, the PCV system compensates and purges combustion gasses from the crankcase. But when accumulated wear (or poor fit) become excessive, uncontrolled blowby develops that can overwhelm the PCV system.
Blowby is influenced dominantly by the degree of cylinder wall glazing, cylinder wear, piston ring clearances (fit) and wear, and abnormal rocking of the pistons. Evidence for blowby is abnormal puffing of vapors from the crankcase or valve cover breather, oil accumulation in the air cleaner, and in some cases, chronic recurring oil leaks past passive gaskets and seals that resist routine correction.
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some leakage past the rings is unavoidable
and the main reason why we have to change the engine oil.
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How old is the 350?
i hate to say it, but i think, if there is lots of smoke coming out of the breathers to the point that it's very noticeable, then the engine does not have long until it needs to be rebuilt or replaced.