PCV Question
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
PCV Question
I have bought several PCV valves as the current one opens wide at only 6" of vacuum, floods the carb with too much air causing hi idle and increasing oil consumption. PCVs marked with numbers such as 18 doesn't necessarily mean it takes 18" to open it wide. In fact a #18 opens at 12" and a #20 opens at 16". I have temporarily put a resrictor orifice inside the PCV hose limiting it's ability to suck too much air and all is well with the carb. Before I could not achieve 800rpm idle but with the PCV disconnected or resricted I'm fine. Now this is temporary but eventually I want the right PCV, one that is 1/4 open at idle which is 16.5" vacuum. Let me know if you know the right one, and no I do not want push in breathers becuase while good when brand new they get oil soaked after time and leave oil misting all over the valve cover when I do my extended WOT cruises.
Last edited by Cali,68,L-79; Apr 13, 2005 at 10:43 PM.
Drifting
Joined: Feb 2005
Posts: 1,738
Likes: 2
From: San diego ca
Why not plumb the connection on the passenger side to the air filter - that way you have one PCV (once you find the one you like)on one side and no push in breather on the other side...
also - tommorrow is Escondido - crusin grand and we will be there.
E
also - tommorrow is Escondido - crusin grand and we will be there.
E
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Originally Posted by fauxrs2
Why not plumb the connection on the passenger side to the air filter - that way you have one PCV (once you find the one you like)on one side and no push in breather on the other side...
also - tommorrow is Escondido - crusin grand and we will be there.
E
also - tommorrow is Escondido - crusin grand and we will be there.
E
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
Originally Posted by carnutt94
ever consider a crank-case evac system..(valve cover breather connected to exhaust) down near header collecter??? used alot in drag racing...Allan
Intermediate
Joined: Apr 2005
Posts: 43
Likes: 0
From: near Elsberry Mo StL C-3 Sharks
Don't have any pics ..but i have seen some done very nicely...using an oil breather cap with a hose port and steelbraided line going down to header collecter...ask a good speed / drag shop about it...usually good for a little time off your e.t....couple 10ths more or less....get an oil breather cap that won't breathe on your valve covers...closed except for where it goes in valve cover and where the hose mounts......Allan
Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
Originally Posted by carnutt94
ever consider a crank-case evac system..(valve cover breather connected to exhaust) down near header collecter??? used alot in drag racing...Allan
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Race Director
Joined: Jun 2000
Posts: 10,046
Likes: 675
From: FL
Originally Posted by Cali,68,L-79
Please elaborate.
From the Mr. Gasket site:
http://go.mrgasket.com/AskTechResult...dID=0&ID=34200
Question: Brand: MrGasket
I'm thinking about putting the crankcase evacuation system on my engine. I know what the positives are of the system, but are there any negatives?
Solution:
The system will only work with no exhaust so there is plenty of flow.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
How are u testing them - brake vac pump? Measure flow?
Originally Posted by Cali,68,L-79
I have bought several PCV valves as the current one opens wide at only 6" of vacuum, floods the carb with too much air causing hi idle and increasing oil consumption. PCVs marked with numbers such as 18 doesn't necessarily mean it takes 18" to open it wide. In fact a #18 opens at 12" and a #20 opens at 16". I have temporarily put a resrictor orifice inside the PCV hose limiting it's ability to suck too much air and all is well with the carb. Before I could not achieve 800rpm idle but with the PCV disconnected or resricted I'm fine. Now this is temporary but eventually I want the right PCV, one that is 1/4 open at idle which is 16.5" vacuum. Let me know if you know the right one, and no I do not want push in breathers becuase while good when brand new they get oil soaked after time and leave oil misting all over the valve cover when I do my extended WOT cruises.
We do need someone to research this as we have plenty of crankcase press problems here on the forum. The PCV sys is the only sensible evac sys for a mild street mtr when compared to others - other than just a breather. That PCV should just crack open/restricted at idle/hi-vac and move max open at low vac/WOT. But at zero vac or pos press it needs to seat shut (spring forces past max open position to seat shut) to protect against backfires.
So if it pulls too hard at idle and flows too much air through crankcase/into intake u could always restrict the other end that pulls from the A/C - that way it should maintain hi vac on crankcase but reduce flow/intake mix dilution. Be careful in how u block that vac hose/line so the restrictor dosen't become loose and enter the vlv cover.
Now a performance engine will just have lower vac at idle - maybe 13" or less - but the rest of PCV should operate the same.
I don't know how they rate these things but sometimes on a Thursday or Friday afternoon u can find a bored NAPA counterman that will look through the books with u. Maybe the Fram or Purolator websites will have some info - or even send thier tech dept an email.
And if u find something that makes sense maybe we can get it into the new archive sys.
cardo0