breathers

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Sep 27, 2004 | 01:49 AM

panchop

Thread Starter

Melting Slicks

Joined: Dec 2000

Posts: 2,130

Likes: 1

From: mesa,az

breathers

for my new SB i am using a brerather in each valve cover. i was planing on venting them into the manifold or carb. some of the things i have read here latley make me think i am not doing the right thing ? can someone lay it out for me.
thanks
greg

Sep 27, 2004 | 02:14 AM

comp

Team Owner

Joined: Sep 2003

Posts: 88,393

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From: eville in

what is your combo.??? and there are a few members in Fla. that may
be slow to see

Sep 27, 2004 | 09:36 AM

ralph

Le Mans Master

Joined: Feb 1999

Posts: 6,172

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From: somers, ny

Panchop....I've tried a few configs with my 406 (see thread - Any problem doing this??). With the stock setup (PCV/no breather), i was building crankcase pressure. With just breathers, i would get fumes. And with breathers and PCV, it became a vacuum leak that sucked considerable oil with it. Now i'm trying 2 PCVs...putting the crankcase under vacuum and providing two ventilation paths for WOT. Don't know if it's going to work yet............

Sep 27, 2004 | 10:26 AM

SWCDuke

Race Director

Joined: May 2000

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A typical PCV system for a carbureted engine uses manifold vacuum to draw fresh air into the crankcase, which mixes with crankcase gases (mostly unburned fuel air mixture blowby) and draws them into the inlet manifold.

Flow is regulated by a valve, and the valve must have an anti-backflow provision to keep a carb backfire from propagating to the crankcase and cause an explosion.

PCV system schematics are contained in nearly all GM service manuals.

Duke

Sep 27, 2004 | 11:26 AM

Vetterodder

Safety Car

Joined: Feb 1999

Posts: 3,631

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From: Fountain Hills AZ

Do it like a stock system as Duke described. PVC valve to carb and fresh air from breather or air cleaner base. Many after market air cleaners come with the fitting but not the spark arrestor-filter. If yours doesn't have it you can get one at any auto parts supply. If you decide to use a breather for the fresh air side expect some oil film in the engine compartment and the smell of oil.

Sep 27, 2004 | 06:39 PM

skid

Racer

Joined: Feb 2004

Posts: 324

Likes: 0

From: Wet Coast

My 406 uses oil and it really shouldn't because it is fresh with new heads. I have a PCV valve which is connected to the carb, and I have the stock valve cover breather hose that is connected into the air cleaner case. Is this valve cover breather hose helping suck oil into the carb from the pcv valve? Is this what you have experienced Ralph?

Sep 27, 2004 | 07:04 PM

ralph

Le Mans Master

Joined: Feb 1999

Posts: 6,172

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From: somers, ny

Mine started pinging real bad. As i dug into it, i found a puddle of oil in the intake that i traced back to the PCV valve. I put a compressor filter inline with the PCV hose and it stopped the oil from reaching the intake. While it seemed like a lot, it was only about a shot glass full every 300-400 miles, so i doubt it's the cause of your oil consumption. However i think too much ventilation moves too much air and oil with it...and having a larger engine makes it's worse. It's either that or i'm getting way too much oil up into the valve covers. Too much ventilation thru the PCV is also basically a vacuum leak, which is screwing up my ECM a bit. If the double PCV doesn't work out, i think i'm just going to run hoses off the valve covers to under the car somewhere it will blow off.

Sep 28, 2004 | 09:38 AM

TrueBlue ChevyDude

Drifting

Joined: May 2001

Posts: 1,630

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From: Brandywine, Chester and Ridley Valleys Pennsylvania

Just stating the obvious, but letting oil drip anywhere it could come near tires or brakes is a bad idea. Don't hard-hittin' folks route a tube from each valve cover into a Header-Evac setup?