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Engine Breathing

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#31 Kt1966


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Posted 08 July 2019 - 08:33 AM

That's interesting. Thanks. My preference would certainly be to go for the additional timing breather if that will do the job - neater and simpler if it'll work.

I've got a 1400,SW5,HiF44,well ported head and all the trimmings.

If I ended up with "just" the 3 breathers then do you feel that will do the job?

#32 unburntfuelinthemorning


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Posted 08 July 2019 - 10:05 AM

That's interesting about the low speed part... What did he use as a PCV ??


I have a HiF44 and it would certainly be a lot less faff to just add the timing case breather - I just want something which will work sufficiently well.


I'm interested why you would suggest getting rid of the fuel pump one ? - surely more is better ??


Many thanks

I don't know what he used as a PCV, probably some generic one.


The standard system plumbed from two breathers into an SU will work sufficiently well as you require. 


If you are ventilating to atmosphere then the more breathers the better as you need to keep the crankcase pressure as close to atmospheric as possible.


With the standard ventilation system air enters through the oil filler cap vent and is drawn through the engine and out through the breathers into the induction system.  This purges the crankcase air with fresh air. 


My thinking is that having a breather at both ends of the engine to draw out the crankcase air will reduce the likelihood of pockets of dirty air getting stuck inside the crankcase. 


If there is only one breather as on small bores on the tappet chest cover then air is drawn in through the oil filler cap, travels down the pushrod holes and exits the engine without flowing through the crankcase.


Having one breather on the clutch housing and one on the timing cover allows most of the air to be purged.  The fuel pump outlet breather would work too but you may get some stale crankcase air around the timing gears.

#33 Steve220


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Posted 08 July 2019 - 07:20 PM

I know the topic has slghtly changed, but If anyone is remotely interested I sorted out the breathing on my MPi... as proved after it blew :lol: The smoke poured out of all the breathers well without feeling or looking like a pressurised air line. I managed to get an S bend onto the transfer case breather to allow me use of it from under the boost pipe!

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