11 replies to this topic

[olly33]

Hi,i have the current setup below in my mini mayfair,fitted with cooper s front subframe.

My question after doing a search,and reading its recommended to use the standard setup of the breather pipes to the carb?

 

1257cc with a 276 cam, new followers, and an HIF44 carb with pan k&n filter, also a central oil pick up was fitted at this time, this has all been set up on a rolling road.The head is a morspeed stage 4 with bigger valves and double springs.

 

Also a  2" WP straight exhaust from a 3;1 manifold,

 

 

would i be correct,as i currently have a small filter on the clutch housing breather,and the other side breather next to rad,i have just an open pipe coming from it,which i assume should either be fitted with another filter,or do away with both filters and T piece them together to the pipe coming off the carb,but which pipe on carb,i have 2? is the thinner one an overflow? Both carb pipes are currently open.

 

The open pipe breather, when running emits what seems like steam.....I ask as i would prefer the best setup for the engine mentioned above,also has vented oil filler cap,but the car was originally setup on rolling road by previous owner,so if i change the setup will anything need altering?? cheers all in advance

 

[Dan]

  The best thing for the health of the engine is to connect it all up to the carb.  Yes it will need the tuning altered to cope, I can't imagine it's working as well as it could it the carb emissions connection is open.  Yes the smaller outlet at the carb is the overflow which will ideally have a pipe connected to carry any overflow under the car.  If this is a racer though the best thing might be to leave an open vented system, but to take the breathers to a catch tank (many series' regulations require this).  The worst way to arrange a breather is through an open pipe, the steam you can see is largely water vapour but contains a lot of oil too.  This will end up all over your engine bay.  The breather filter is only slightly better than this, it traps some of the oil but still allows a lot through.

[zerobelow]

My engine builder was very specific that I need to run 1/2" ID hose from the breathers to a >1 liter catch tank, and not to tee them together before the tank. Then, run a hose from the catch tank and let it dangle. I haven't fired it up yet (tomorrow!), so I don't have feedback on the setup yet. And this is for a primarily track setup.

[Ethel]

Your engine can't really be set up with an open carb breather connection. It will allow differing amounts of air to bypass the venturi depending on the load & throttle position, making metering the fuel nigh on impossible. It could be set overly rich to compensate for the leak at idle and maybe needled to be overly lean at full throttle. I can't believe anyone could be capable of operating a rolling road and attempt to set a car up with such an obvious air leak, so perhaps it's been left open since?

[olly33]

The best thing for the health of the engine is to connect it all up to the carb.  Yes it will need the tuning altered to cope, I can't imagine it's working as well as it could it the carb emissions connection is open.  Yes the smaller outlet at the carb is the overflow which will ideally have a pipe connected to carry any overflow under the car.  If this is a racer though the best thing might be to leave an open vented system, but to take the breathers to a catch tank (many series' regulations require this).  The worst way to arrange a breather is through an open pipe, the steam you can see is largely water vapour but contains a lot of oil too.  This will end up all over your engine bay.  The breather filter is only slightly better than this, it traps some of the oil but still allows a lot through.

Dan,so the thinner of the 2 pipes on the carb is the overflow? And does it not matter if i connect it all to the carb,even with the engine moods that have been done,all by previous owner and still not run in as such? Cheers

Your engine can't really be set up with an open carb breather connection. It will allow differing amounts of air to bypass the venturi depending on the load & throttle position, making metering the fuel nigh on impossible. It could be set overly rich to compensate for the leak at idle and maybe needled to be overly lean at full throttle. I can't believe anyone could be capable of operating a rolling road and attempt to set a car up with such an obvious air leak, so perhaps it's been left open since?

Ethel ,the pipe has been disconnected at some point since setup i think as i bought the car needing to finish things off .

[Dan]

And does it not matter if i connect it all to the carb,even with the engine moods that have been done,all by previous owner and still not run in as such?

 

  By that do you mean you are worried it will adversely affect the engine?  It won't.  It's better for the engine to use positive ventilation, especially a new engine actually.  Unless your engine has been spectacularly badly built there will not be even remotely enough fuel blowby in a new build to wash any oil away, but as there will be some amount then positive ventilation will draw the blowby out rather than letting it accumulate as open venting will.  If you actively draw the crud (fuel and exhaust blowby, exhaust being mostly water, various volatiles evaporating off the hot oil and other stuff) and replace it with clean air then the inside won't varnish up, the oil will not absorb water and fuel and so will last longer, the pressure inside will be lower so oil won't be driven out of seals as easily and all your new seals and gaskets last longer, and there will be less mass for the crankshaft to fight its way through.  As long as there are breather cans on both ends there won't be a huge amount of oil vapour in what is being drawn out so it won't affect the fuelling all that much.  The air leak will definitely be a problem though so either hook it all up properly or plug the hole in the carb if you want to use a catch tank.  Either way some minor re-tuning will probably be needed.  Yes the smaller pipe is the overflow.

Edited by Dan, 14 December 2013 - 11:05 PM.

[olly33]

Cheers Dan,i think i will link it all together to the carb,and get rid of the one filter that's already fitted.
I probably be asking more questions on here when i am unsure about certain things. Olly

[daenesh]

i fitted a oil catch tank to my breather and let the pipe flow out.. closed up the hole on the carb with a stopper as well.. been running like that for years now.. heres a picture 

 

 

 

Edited by daenesh, 17 December 2013 - 09:09 AM.

[herdy]

i fitted a oil catch tank to my breather and let the pipe flow out.. closed up the hole on the carb with a stopper as well.. been running like that for years now.. heres a picture 
 
 
 

Is that two alternators that you're running

[phil hill]

 

i fitted a oil catch tank to my breather and let the pipe flow out.. closed up the hole on the carb with a stopper as well.. been running like that for years now.. heres a picture 

Is that two alternators that you're running

 

Air conditioning Compressor !!

 

The condenser and it's fan is in front of the coil.  

 

Phil.

[herdy]

i fitted a oil catch tank to my breather and let the pipe flow out.. closed up the hole on the carb with a stopper as well.. been running like that for years now.. heres a picture

Is that two alternators that you're running

Air conditioning Compressor !!
 
The condenser and it's fan is in front of the coil.  
 
Phil.

Ah right fair enough. Was just having a nosey through some of the pics on their photo bucket and it looked like two alternators

[daenesh]

 

 

 

i fitted a oil catch tank to my breather and let the pipe flow out.. closed up the hole on the carb with a stopper as well.. been running like that for years now.. heres a picture

Is that two alternators that you're running

Air conditioning Compressor !!
 
The condenser and it's fan is in front of the coil.  
 
Phil.

Ah right fair enough. Was just having a nosey through some of the pics on their photo bucket and it looked like two alternators

 

 

haha its the air conditioner compressor.. and thanks for browsing my pics :)