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.

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.

Here is an old thread that may help. viewtopic.php?t=44722

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.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I went from the rocker cover to a T piece then to both my carbs....? Is this ok??




I've also got a breather on the clutch case

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http://www.youtube.com/user/Hanras

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).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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?

Forgot to mention the brake booster is teed off from one of the 2 ports (connected) on the manifold...

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

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

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.

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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http://www.youtube.com/user/Hanras