Breather 347
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silverlx50
15 Year Member
- Apr 4, 2007
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There's some good info here, my only suggestion would be to make sure you add a catch can to the system if you are already adding PCV or new lines to the system.
marcelo
Active Member
do this ...https://lmr.com/item/SB-261522/Mustang-Screw-In-Valve-Cover-Breather-86-00
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marcelo
Active Member
hahahahahaha ..... is that so ?? lean conditions .... ok ok ...and what for, you have the Oxygen Sensors and the ECU for ?? if it causes any lean conditions ..sensors will detect and sending info to the ECU ...ECU reacts inmediately and sprays a little more gasoline into the Engine to get the right AFR ... If I understand right ...thats why engines have O2 Sensors and ECUs.....??? and if you run a 347 with Victor Intake..then your willing to rev up +6k and that can cause a lot of other reasons leaning out the Engine ...should run a AFR gauge anyways..
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- Mar 2, 2015
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This routing will cause a lean condition. The engine is calculating air volume from the MAF sensor. Air is entering the breather in the oil fill location and going through the hose to the throttle body. This is not the correct way to do that. The oil fill tube should be capped off. That will allow the already metered air in the engine to flow into the throttle body under acceleration ( when pressure builds )...when cruising or idling the PCV would pull vapors into the intake allowing flow to come from the hose at the throttle body...into the engine...and out the pcv....to the intake.
So...yes....Marcelo...that way is wrong.
It can be tuned around...but is still not right. Air must flow...kinda like water. If you have an open breather then you shouldn't have that hose to the TB....or the hose hooked up from the PCV to the intake.
On our PCV system theres a clean and a dirty side. There should be a breather can on one side and a catch can on the other especially if boosted. Open filters do work with the PCV system deleted but will smell like fumes and will make messes of the valve covers over time. If you use open breathers and the factory PCV valve it will cause lean idle conditions unless you have a chip or tune that gets around that issue.
Vehicles fueling adaption strategy is limited. O2 sensors help the car stay in the operating range. Too lean or rich and the computer can not compensate for it.
^^what he said^^
Hahahahaha right back at ya!!!
And leaving the spark plugs loose will cause a lean condition that the computer can't compensate for too.
Ask me how I know.
Hahahahaha right back at ya!!!
And leaving the spark plugs loose will cause a lean condition that the computer can't compensate for too.
Ask me how I know.
marcelo
Active Member
you maybe right from a theoretical standpoint ....next time I go for a ride ..... I do a test ..runing at 2k with open filler and runing 2k with filler hole taped...making data log of both runs .....wondering if there is any difference ?? 
might be..... Ill let you know as soon as possible... 
might be..... Ill let you know as soon as possible...
Let me take the pcv thing another step, this is an observation, I have witnessed several engines that have no pcv but do have a breather in at least one valve cover.
Every one of them had oily, seeping oil pan, valve cover and intake leaks at the china walls. The breather(s) were oily.
We know the pcv pulls vapor from the inside of the engine that contains contamination and burns it in the combustion cycle. This also helps keep the inside of the engine cleaner, so why not use one?
As far as the 'un metered' air thing goes, the efi system is designed around a closed air intake system, the computer has a small amount of adjustments it can make.
I'm not saying anyone is wrong just that un metered air and/or no pcv is not the correct way to do it.
Every one of them had oily, seeping oil pan, valve cover and intake leaks at the china walls. The breather(s) were oily.
We know the pcv pulls vapor from the inside of the engine that contains contamination and burns it in the combustion cycle. This also helps keep the inside of the engine cleaner, so why not use one?
As far as the 'un metered' air thing goes, the efi system is designed around a closed air intake system, the computer has a small amount of adjustments it can make.
I'm not saying anyone is wrong just that un metered air and/or no pcv is not the correct way to do it.
marcelo
Active Member
hell of a game ??!!! with that air stuff....hahaha I also use a PCV ..from the back of the intake (original) but not that much oil on it ..had a catch can installed but never a drop of oil in it ..so its not in use anymore...i forgot that my engine is Speed Density ... if that makes a difference ..almost shure it does ???
Even less adjustment ability with sdhell of a game ??!!! with that air stuff....hahaha I also use a PCV ..from the back of the intake (original) but not that much oil on it ..had a catch can installed but never a drop of oil in it ..so its not in use anymore...i forgot that my engine is Speed Density ... if that makes a difference ..almost shure it does ???
Wait until your engine loosens up. The catch can and PVC will help keep things clean. A 1965 Olds rocket that has worked hard in the family since new had a primitive breather system. The valve cover breather vented directly into the snorkel, with a big, primitive valve, and it needed Gunk engine cleaner in the breather with each new air filter by 100k miles. A rebuild and a real PVC valve keeps it much dryer outside like the General’s theory. And it does not smell like an old car while running at idle.
hell of a game ??!!! with that air stuff....hahaha I also use a PCV ..from the back of the intake (original) but not that much oil on it ..had a catch can installed but never a drop of oil in it ..so its not in use anymore...i forgot that my engine is Speed Density ... if that makes a difference ..almost shure it does ???
Steel1
Mustang Master
Not an expert but just my experience.
393w n/a Pimpxs SD, no pcv provisions on lower intake, stock 5.0 valve covers with oil fill on each (custom fabbed by me.. lol ) both capped,
lines from each nipple on oil fills to catch can w/breather on top.
No oily mess on valve covers , catch can gets maybe a drop of oil every 500mi.
393w n/a Pimpxs SD, no pcv provisions on lower intake, stock 5.0 valve covers with oil fill on each (custom fabbed by me.. lol ) both capped,
lines from each nipple on oil fills to catch can w/breather on top.
No oily mess on valve covers , catch can gets maybe a drop of oil every 500mi.
- Mar 2, 2015
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Speed density does make a difference @marcelo . The air coming in isn't metered....it runs off of readings from the MAP sensor. In that case, as long as the leak is before the throttle body it won't matter. ( computer wouldn't know the difference ) The air coming through the pcv hose to the intake at idle would already be compensated for in the strategy of the ECU. Fresh air through the intake tube is the same as fresh air through the open filter at idle. In that respect you are correct. Now, at full throttle the computer fuel trim would expect to see some fumes from the crankcase. It probably would not be a big enough amount to make a huge difference in the performance of the car. The computer ( in your case ) should be able to compensate. That situation would be like having a brand new engine that has very little blow by.
On a MAF car any air leak after the MAF sensor will screw things up.
On a MAF car any air leak after the MAF sensor will screw things up.
marcelo
Active Member
ok ... ..with different setup ... datalog does not show any changes in AFR readings at all ... changes must be that small cant be detected or there are no changes at all ... sorry guys .. you all might be right .. but my engine gives a sh...t if tube is on or off or oil filler is closed or open etc... 331cu Tubular Gt intake, F cam, Aluheads, LT Headers .. nothing special ok engine is new ..less then 1000miles
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speed density does not measure incoming air flow (I think it does not on stock setups ?)How does your computer measure air flow?
I'm thinking you have an aftermarket controller and an afr gauge, just trying to educate myself here.
It estimates (calculates) airflow using manifold Absolute pressure, RPM, other sensors, and charts made by a magic gnome hidden in the kick panel next to the computer.
I know all about that magic gnome. And I know how speed density works, just trying to point out the correct way efi needs to be configured, a properly configured pcv system will help keep the inside of the engine clean, oil and moisture vapors are sucked into the intake and burned off in the combustion process.
Post #35 explains it very well.
@7991LXnSHO and @90sickfox I think will agree with me when I say remove the pcv and stick a breather on the valve cover then come back here after 50k miles and I would be surprised if that engine is not seeping oil from the oil pan, valve covers, rear main leaving the engine and engine compartment a stinky oily mess.
I've seen it too many times.
Post #35 explains it very well.
@7991LXnSHO and @90sickfox I think will agree with me when I say remove the pcv and stick a breather on the valve cover then come back here after 50k miles and I would be surprised if that engine is not seeping oil from the oil pan, valve covers, rear main leaving the engine and engine compartment a stinky oily mess.
I've seen it too many times.
Boostedpimp
Dirt-Old 20+Year Member
Those mods on a factory speed density car wouldn't work... what engine management system are you using?
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