anyone know where the PCV/Breathers can be located other than through the top of the rocker covers? I dont want anything through the top of my rocker covers if possible
cheers
PCV valve
Started by
_the gts_
, Aug 06 2010 10:08 PM
40 replies to this topic
#3
rodomo
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Posted 07 August 2010 - 01:27 PM
The very 1st of the Holden V8's had tube out of the top of the timing cover like Chev.
Hard to find one of those covers now days I'd reckon but you might be able to tap some fittings into the same area on a late cover?
My Range Rover V8 runs the breather off the webbing across the "V" below the inlet manifold at the rear of the engine (standard)
Hard to find one of those covers now days I'd reckon but you might be able to tap some fittings into the same area on a late cover?
My Range Rover V8 runs the breather off the webbing across the "V" below the inlet manifold at the rear of the engine (standard)
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Edited by rodomo, 07 August 2010 - 01:28 PM.
#4
_greenmachine215_
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Posted 07 August 2010 - 04:40 PM
id put it in the bin, run a catch can system instead
#5
_Squarepants_
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Posted 07 August 2010 - 05:01 PM
id put it in the bin, run a catch can system instead
Yeah, all good and well until you get pulled over by the fuzz and defected 'cause you have engine gasses venting to atmo.
I have the same issues atm trying to hook up all the crap on my triple webered 202.
I don't know much about the v8 breathers but on the 6's I have seen them run into the fuel pump blanking plates (if running an electric pump) and into the side plates.
However I think PCV's have to be mounted vertically so the valve works properly.
Maybe you could weld a fitting onto the back/side of the rocker covers with an elbow facing vertically??? Dunno, just a suggestion.
#6
_the gts_
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Posted 07 August 2010 - 05:59 PM
Rodomo Its all about cleaqning the engine bay up, so dont want to put one on the timing cover. Are you saying that the rover V8's have them in the valley on the inlet manifold?
yea squarepants that was one of my ideas out the back of the rocker cover.
Isnt a PCV only a check valve? if so it would be possible to source ones that work in any mounting position.
yea squarepants that was one of my ideas out the back of the rocker cover.
Isnt a PCV only a check valve? if so it would be possible to source ones that work in any mounting position.
#7
_Squarepants_
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Posted 07 August 2010 - 06:17 PM
Isnt a PCV only a check valve? if so it would be possible to source ones that work in any mounting position.
Yeah, but they are supposedly calibrated to suit the flow of the engine blowby and manifold vacuum.
There's a bit of an art to setting them up properly, which is why most people get rid of them and use the catch can breather system.
Read this:
http://www.gmh-torana.com.au/forums/index.php?showtopic=47546
As I am in the process of doing the same thing to my 202 and this is what I've come up with so far... Not ideal, but will suit a road car... Hopefully.
#8
View GaragePosted 07 August 2010 - 09:25 PM
Put it anywhere that gets crank case pressure without pulling too much oil with it. Removing it entirely is all very well for a race engine that does high revs all day long and has massive breathers (which make the engine bay ugly again) but in my opinion the PCV system is a lot more refined for general street use.
#9
rodomo
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Posted 07 August 2010 - 10:46 PM
Yes, in the valley, but tapped into the block, not the inlet manifold.Are you saying that the rover V8's have them in the valley on the inlet manifold?
This pic shows the boss where mine is tapped. This must be a later block.
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#10
_the gts_
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Posted 07 August 2010 - 11:53 PM
so in theory drilling and tapping one into the centre of the manifold hidden just behind the carb would be a good spot and work well?
Squarepants - i read that topic, it all has me confused at the moment but i like your drawings!!
Anyone know where timed vacuum comes from? can the PCV be plugged into that on a Demon carb?
Squarepants - i read that topic, it all has me confused at the moment but i like your drawings!!
Anyone know where timed vacuum comes from? can the PCV be plugged into that on a Demon carb?
#11
rodomo
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Posted 08 August 2010 - 12:25 AM
so in theory drilling and tapping one into the centre of the manifold hidden just behind the carb would be a good spot and work well?
What my pic shows is where to drill the block to draw the fumes FROM.
Where the fumes GO TO would be somewhere on your induction (manifold if PCV or aircleaner if breather)
You would need to tap the block twice.
Edited by rodomo, 08 August 2010 - 12:28 AM.
#12
_the gts_
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Posted 08 August 2010 - 12:51 AM
Sorry Rodomo I should have been clearer
I was thinking of drilling a hole in the manifold valley behind the carb for the PCV to come FROM
It will GO TO manifold vacuum either the vacuum port on the carb or possibly the timed vacuum port on the carb or even a hole drilled into
If the PCV is basically only a breather with for the block with a check valve in it then this should be ok shouldnt it?
I was thinking of drilling a hole in the manifold valley behind the carb for the PCV to come FROM
It will GO TO manifold vacuum either the vacuum port on the carb or possibly the timed vacuum port on the carb or even a hole drilled into
If the PCV is basically only a breather with for the block with a check valve in it then this should be ok shouldnt it?
#13
rodomo
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Posted 08 August 2010 - 01:02 AM
Yep, I'm with you now. Drill holes here?
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#14
_the gts_
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Posted 08 August 2010 - 02:04 AM
Yep That is pretty much where it is going to go.
Just read that the early corvette's had the 'in side' tapped into the oil fill tube which is in the manifold. Trick flow also do a ford manifold with the pcv in it. so that has got to be a good hiding spot for it!!!!!!
Thanks for you help rodomo
hey why did you put 3 holes on your picture? it should only need 2 shouldnt it?
Just read that the early corvette's had the 'in side' tapped into the oil fill tube which is in the manifold. Trick flow also do a ford manifold with the pcv in it. so that has got to be a good hiding spot for it!!!!!!
Thanks for you help rodomo
hey why did you put 3 holes on your picture? it should only need 2 shouldnt it?
#15
Posted 08 August 2010 - 08:04 AM
I think he is saying one at the back for PCV FROM and one for breather FROM, plus the one in the runner for the PCV TO and one in the air cleaner (not shown) for breather TO. I wonder though if its not such a good idea to have the PCV TO in only side of a dual plane manifold, this might be a pain with fuel mixtures?
#16
rodomo
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Posted 08 August 2010 - 08:30 AM
hey why did you put 3 holes on your picture? it should only need 2 shouldnt it?
Just showing possible options of where to drill.
You would have to take into account what is under the manifold at those points and how it might also interfere with the distributor.
#17
_the gts_
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Posted 08 August 2010 - 11:49 AM
My manifold is a Victor Jnr single plane on a chev so the 'TO' will be going directly under the carb at the back. I will take a picture today and post it.
76Hatch, I am not planning on having a breather. as far as I am aware the engine only needs to be able to get rid of remove positive pressure in the crankcase.
my thoughts are that it is probably the same as gearboxes that i build at work. they must have a breather, otherwise when they warm up the air inside expands and creates enough pressure to blow seals out. Although engines have a feww more variables I think it must be along the same principal. I would hate to blow the rear main out!!
76Hatch, I am not planning on having a breather. as far as I am aware the engine only needs to be able to get rid of remove positive pressure in the crankcase.
my thoughts are that it is probably the same as gearboxes that i build at work. they must have a breather, otherwise when they warm up the air inside expands and creates enough pressure to blow seals out. Although engines have a feww more variables I think it must be along the same principal. I would hate to blow the rear main out!!
#18
TerrA LX
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Posted 08 August 2010 - 01:46 PM
The engine has to breathe, if it is just under vacuum it will not ventilate.
#19
_the gts_
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Posted 08 August 2010 - 01:54 PM
So how does it breathe other than the PCV if legally on a street registered car you are not allowed to have a breather that vents to atmosphere?
Edited by the gts, 08 August 2010 - 01:59 PM.
#20
TerrA LX
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Posted 08 August 2010 - 02:00 PM
It draws fresh air IN from the air filter under vacuum, the old systems pre HQ style vented to the atmosphere, because they were not under vacuum.
I hope that helps clarify it.
I hope that helps clarify it.
#21
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Posted 08 August 2010 - 02:13 PM
AHHH the penny drops!!!
can this be done at the front and back of the intake valley instead of rocker covers? I still dont understand why it needs fres air into the crankcase
can this be done at the front and back of the intake valley instead of rocker covers? I still dont understand why it needs fres air into the crankcase
Edited by the gts, 08 August 2010 - 02:15 PM.
#22
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Posted 08 August 2010 - 02:21 PM
GTS look at it this way, there will be no flow if the pressure (vacuum) is not equalised.
Doesn't really matter where the air enters and exits the motor so long as it is ventilating the crank case.
Doesn't really matter where the air enters and exits the motor so long as it is ventilating the crank case.
#23
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Posted 08 August 2010 - 02:39 PM
It uses the fresh air from the breather to dilute the engine fumes going through the PCV for less pollution.
The breather is also there for WOT (wide open throttle) conditions where there is very little manifold vacuum and the amount of blow by is greater than what can flow through the PCV.
I don't understand why open engine breather filters are illegal as the standard breather is fitted to the air filter cover which is not sealed from atmosphere at all. Sure, the gasses are more likely to get sucked back into the engine to be reburnt from there but it still has potential to escape to atmosphere.
The breather is also there for WOT (wide open throttle) conditions where there is very little manifold vacuum and the amount of blow by is greater than what can flow through the PCV.
I don't understand why open engine breather filters are illegal as the standard breather is fitted to the air filter cover which is not sealed from atmosphere at all. Sure, the gasses are more likely to get sucked back into the engine to be reburnt from there but it still has potential to escape to atmosphere.
#24
_the gts_
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Posted 08 August 2010 - 03:49 PM
doesnt some of the pressure from compression pass the rings and end up in the crankcase?
If a PCV is a check valve, which it is, it should-
1 - open if the vacuum overcomes the spring in the valve which would may create a vacuum in the crankcase - apparently that is one of the advantages of a dry sump system.
2 - open with internal cranckase pressure from ring bypass, engine heating up etc
3 - in both of the above situations there is no chance of overpressuring the crankcase.
4 - if there is no vacuum or no crankcase pressure there will be no breathing, the crank case has neutral pressure is that a bad thing?
so why does the crankcase need fresh air?
If a PCV is a check valve, which it is, it should-
1 - open if the vacuum overcomes the spring in the valve which would may create a vacuum in the crankcase - apparently that is one of the advantages of a dry sump system.
2 - open with internal cranckase pressure from ring bypass, engine heating up etc
3 - in both of the above situations there is no chance of overpressuring the crankcase.
4 - if there is no vacuum or no crankcase pressure there will be no breathing, the crank case has neutral pressure is that a bad thing?
so why does the crankcase need fresh air?
#25
_Squarepants_
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Posted 08 August 2010 - 04:57 PM
doesnt some of the pressure from compression pass the rings and end up in the crankcase?
Yes
If a PCV is a check valve, which it is, it should-
1 - open if the vacuum overcomes the spring in the valve which would may create a vacuum in the crankcase - apparently that is one of the advantages of a dry sump system.
Yes, when the manifold vacuum overcomes the spring pressure, or when crankcase pressure overcomes the spring pressure
2 - open with internal cranckase pressure from ring bypass, engine heating up etc
Yes, but the PCV valve creates a big restriction and apparently the flow from blow by is greater than a PCV system can support
3 - in both of the above situations there is no chance of overpressuring the crankcase.
See #2
4 - if there is no vacuum or no crankcase pressure there will be no breathing, the crank case has neutral pressure is that a bad thing?
I don't think so, but I think you'd only get this scenario when the engine is switched off
so why does the crankcase need fresh air?
Just to dilute the gasses coming from the crankcase through the PCV to reduce pollution and add more clean air to the inlet mixture for a better burn thus better power and economy
I tried running 2 PCV's and no breather and it created massive crankcase vacuum which in turn reduced oil pressure and generally played havoc on the way the engine ran. Potentially it could also damage gaskets/seals. A vacuum in the crankcase is a good thing, I think, but it has to be moderated. I don't know much about how dry sump systems are set up but I imagine there would be a relief valve in there somewhere to prevent too much vacuum in the crankcase. I could be wrong on this, just speaking from my experiences.
Edited by Squarepants, 08 August 2010 - 04:59 PM.
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