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pcv
https://www.ausmini.com/forums/viewtopic.php?f=2&t=88913		 Page 1 of 2
Author:  kath20 [ Thu Mar 19, 2015 12:09 pm ]
Post subject:  pcv
Hi Guys.Looking for some help re Crankcase ventilation.I have a new complete HS4 1& 1/2" SU carby kit including manifold linkages ect for my Cooper S.The manifold does not have a connection point for the existing PCV valve only an outlet for the vacumn to the brake booster.The 2 carbs have 2 points to connect a hose then to a Y piece & then I am assuming a single hose to the canister on the side cover.Is this all I need to do or do need a PCV valve in the single line after the Y piece?
Cheers Kath.
Author:  gtogreen1969 [ Thu Mar 19, 2015 12:36 pm ]
Post subject:  Re: pcv
I believe that no pcv is needed if hooked into the carbies. Pcv is required if hooked up to the manifold. I will see if i can find an old post about this.
Author:  gtogreen1969 [ Thu Mar 19, 2015 12:39 pm ]
Post subject:  Re: pcv
Here is an old thread that may help. viewtopic.php?t=44722
Author:  drmini in aust [ Thu Mar 19, 2015 1:03 pm ]
Post subject:  Re: pcv
Having just gone through this on a mate's 1380 stroker, I can report that a pcv valve into the manifold sucks harder than the carby vacuum ports do.
If you want a pcv valve fitted, add a tee where the booster hose fitting is.
Author:  kath20 [ Thu Mar 19, 2015 2:01 pm ]
Post subject:  Re: pcv
I thought that was the case.It appears that if you use the 2 carby inlets you dont need a PCV valve.I have run 2 hoses from each carb to a Y piece,then a single hose to the canister on the side cover.
Cheers Kath.
Author:  drmini in aust [ Thu Mar 19, 2015 2:34 pm ]
Post subject:  Re: pcv
kath20 wrote:
I thought that was the case.It appears that if you use the 2 carby inlets you dont need a PCV valve.I have run 2 hoses from each carb to a Y piece,then a single hose to the canister on the side cover.
Cheers Kath.

That would be OK.
We found a single line to only 1 vac port was inadequate on this particular 1380 stroker.
Author:  Hanra [ Fri Mar 20, 2015 8:03 am ]
Post subject:  Re: pcv
I went from the rocker cover to a T piece then to both my carbs....? Is this ok??

Image


I've also got a breather on the clutch case

Image
Author:  drmini in aust [ Fri Mar 20, 2015 8:08 am ]
Post subject:  Re: pcv
Hanra, you would be better to hook the clutch housing breather to the carbs. As a GT was. Sucking from the rocker cover can drag oil fumes out.
You should block the rocker vent or severely restrict it, as it is now you may have too much flow into the carby vac ports which can make it lean down low. Cooper S and 1100S had a breather cap, however I find it works fine with a sealed one too.

Having said this, the rocker cover vent works OK on my 1360 to a pcv valve in the manifold (with vented cap and no flywheel housing breather). :)
Author:  Fishyoil [ Fri Mar 20, 2015 5:45 pm ]
Post subject:  Re: pcv
Doc, I recall you don't have a breather where the fuel pump is correct?

I blanked both fuel pump and transfer case breathers and run the PCV valve from rocker cover to carby manifold. I also have a vented oil filler cap. Would this work ok?
Author:  Fishyoil [ Fri Mar 20, 2015 5:56 pm ]
Post subject:  Re: pcv
Forgot to mention the brake booster is teed off from one of the 2 ports (connected) on the manifold...
Author:  drmini in aust [ Fri Mar 20, 2015 6:39 pm ]
Post subject:  Re: pcv
Fishyoil wrote:
Doc, I recall you don't have a breather where the fuel pump is correct?

I blanked both fuel pump and transfer case breathers and run the PCV valve from rocker cover to carby manifold. I also have a vented oil filler cap. Would this work ok?

Yes that's the setup I run now. It works fine on my 1360. The vented cap only has a tiny air hole in the bottom, an unvented caps is fine too.

re the fuel pump hole, I converted a Cooper S breather to fit on there when I built my 1310 motor. It was fine, UNTIL I went over 4500rpm. Then the crank & rods threw so much oil up it, the car made like JB007's Aston. Was NFG...
If you must put one on there, baffle it somehow. Or buy the MiniMania one, it allegedly is baffled and works.
http://www.minimania.com/part/C-2A265/C ... p-Mounting
Author:  Fishyoil [ Fri Mar 20, 2015 8:19 pm ]
Post subject:  Re: pcv
OK thanks. I actually want to leave it as is with the 2 breathers blanked/blocked but was concerned about the pressure and where it all goes.
Author:  drmini in aust [ Fri Mar 20, 2015 9:30 pm ]
Post subject:  Re: pcv
Fishyoil wrote:
OK thanks. I actually want to leave it as is with the 2 breathers blanked/blocked but was concerned about the pressure and where it all goes.

The only problems with running from the rocker cover to a pcv valve:
1. It is perhaps more likely to pick up & burn oil mist than if you use the flywheel housing breather.
2. It can maybe impair drainback of oil down the pushrod holes. I ran a breather pipe on mine from the rocker cover to the flywheel housing to equalize crankcase pressure.

For a road car, the flywheel housing breather piped to a pcv valve (as std on a Morris 1100S) works just fine. Only problem is on the track, sharp LH bends taken at high rpm can fling some oil up.
Author:  Fishyoil [ Fri Mar 20, 2015 9:58 pm ]
Post subject:  Re: pcv
Excellent point about the oil not draining back properly because it's something that is not often discussed (on the Web anyhow).

I think I now understand and have a few options should new leaks arise.
Author:  Hanra [ Sun Mar 22, 2015 7:48 pm ]
Post subject:  Re: pcv
drmini in aust wrote:
Hanra, you would be better to hook the clutch housing breather to the carbs. As a GT was. Sucking from the rocker cover can drag oil fumes out.
You should block the rocker vent or severely restrict it, as it is now you may have too much flow into the carby vac ports which can make it lean down low. Cooper S and 1100S had a breather cap, however I find it works fine with a sealed one too.

Having said this, the rocker cover vent works OK on my 1360 to a pcv valve in the manifold (with vented cap and no flywheel housing breather). :)



I think my rocker cover cap is a vent type also. I wonder how I could restrict the rocker cover port??
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