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Breather Question..


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#1 myminipickup

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Posted 22 January 2018 - 10:05 PM

Hello,

 

As some of you may know - I'm in the middle of rebuilding my Pickup, with a 1990s A+ 1275 engine, and twin SU carbs - but I'm now confused on the engine breathers...

 

I've got one on the cam cover and one on the clutch housing.... I'm using a manifold for the carbs, which I think should have a breather connected to it - is this correct???? 

 

How do I connect the breathers and should one go to the manifold or not??  Many thanks for your help.

 

Here are pictures showing what I have:

 

26910407_1817730401858859_77626130600722

 

 

27021633_1817730395192193_42527598275747

 

 

26910436_1817730398525526_12020974895949

 



#2 nicklouse

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Posted 22 January 2018 - 10:14 PM

T piece then to carb.

 

are you running a servo?



#3 GraemeC

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Posted 22 January 2018 - 10:23 PM

The breathers don't go to the manifold, that take off is for vacuum for a servo.

(Unless you run the old style PCV which I wouldn't recommend)

Edited by GraemeC, 22 January 2018 - 10:26 PM.


#4 myminipickup

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Posted 22 January 2018 - 10:25 PM

T piece then to carb.

 

are you running a servo?

 

 

No servo - twin carb - where does it end on on the carbs - in the manifold - or is that for the servo??



#5 Stevie W

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Posted 22 January 2018 - 10:26 PM

Or you could run a hose from each breather into a “Y” shaped plastic pipe then run that into a Smiths PCV valve and mount the valve to the port on your twin carb manifold ( a bit like the Cooper S system).

Cheers, Steve.

#6 myminipickup

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Posted 22 January 2018 - 10:27 PM

The breathers don't go to the manifold, that take off is for vacuum for a servo

 

Ok - thanks - so that big pipe connector on the manifold should be plugged if I am not using a servo?



#7 GraemeC

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Posted 22 January 2018 - 10:28 PM

Running twin carbs I would run the breathers to a catch tank - connecting them to both carbs and getting a consistent and even distrubution to each carb could be a nightmare, meaning tuning would be difficult.

 
Ok - thanks - so that big pipe connector on the manifold should be plugged if I am not using a servo?


Yes

Edited by GraemeC, 22 January 2018 - 10:29 PM.


#8 myminipickup

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Posted 22 January 2018 - 10:49 PM

The breathers don't go to the manifold, that take off is for vacuum for a servo.

(Unless you run the old style PCV which I wouldn't recommend)

 

why wouldn't you run the PCV?



#9 GraemeC

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Posted 22 January 2018 - 10:58 PM

Old and unreliable. Not sure you can buy them (or service parts) new now.

#10 nicklouse

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Posted 22 January 2018 - 10:59 PM

Old and unreliable. Not sure you can buy them (or service parts) new now.

this?

http://www.minispare...ck to catalogue


Edited by nicklouse, 22 January 2018 - 11:00 PM.


#11 GraemeC

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Posted 22 January 2018 - 11:16 PM

Yes, but it's out of stock and as it says, the bracket is NLA (although not impossible to fab something).
I'd not noticed you can still by the diaphragm though, so maybe second hand is an option.

Personally I wouldn't bother. Catch can for the breathers and clean air into the carbs.

#12 Dusky

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Posted 23 January 2018 - 12:10 AM

Join the 2 breathers with a Y piece And split Them again into 2 with another Y piece And connect to Both carbs. Crankcase ventilation is imperative. Not worth ditching it on a road car.

#13 Spider

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Posted 23 January 2018 - 05:18 AM

There's other PVC Valves available if that's the way you want to go, but as Graham has touched on, they aren't brilliant, OK, but not brilliant.

 

Have you got your carbs yet?

 

Do these have a CCV Port on them? This is a 1/4" - 5/16" dia tube that comes out of the carb bodies between the butterfly and the piston at around 450 angle.

 

If so, almost as Dusky has suggested, only I'd plug the breather on the timing cover or swap it for one without.



#14 jaysmini1983

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Posted 23 January 2018 - 07:17 AM

Or you could vent them to the air with air small filters, like K&N etc, I have had both and didn't notice any difference in performance or smell. 



#15 Rorf

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Posted 23 January 2018 - 07:41 AM

Do not vent to air, usually the cause of oil leaks and a dirty oily engine compartment - as suggested you need to pull a small amount of the crankcase gases into one of the carbs.






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