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crank case breather
windy - 25/10/15 at 12:06 PM

Hello, help needed. I have a Sierra 1.8 cvh in my Haynes Roadster and fitting bike carbs abut don't know what to do with the crank case breather, pcv etc. I have trawled the forum, but due to my lack of knowledge and experience I have not been able to make sense of what I have read so far, such as oil catch tank and various types of filter. Would some one please explain to me in simple terms what I need to do. Thanks

SJ - 25/10/15 at 01:30 PM

Just connect the crank breater into the filter backplate.

Thats what I did with my CVH [but with the standard carb] and it worked fine.

Don't see the point of a catch tank. Unless the engine is well passed it you shouldn't be getting anything other than fumes out of the breather.
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windy - 25/10/15 at 04:02 PM

Thanks for your reply SJ, I am using bike carbs (zx6r) there is no filter on it yet I will have to make some thing for it. My understanding is that the crank case is under a small amount of pressure and the vapours from the crank case go into the inlet manifold via the pcv, the position this goes in allows the vapours to enter all four cylinders. With bike carbs there are four carburetors individually connected to a cylinder, if I were to connect to the air filter would this not just make a mess in the air filter as I would be introducing the crank case vapours before the air and fuel are mixed. Please correct me if I am wrong, I really do need to get this sorted in my head.

SJ - 25/10/15 at 04:08 PM

I have zx6 cars on my Zetec and this is how mine is set up. I've never seen anything inside the filter.

Stu

avagolen - 25/10/15 at 04:47 PM

Hi, I have a similar setup.

Crankcase breather - remove the internals.

Cam Cover breather - connect to the Crankcase breather with a 'T' (copper in my case).

Connect the other connection on the 'T' to a catchtank.

If the Crankcase breather hose to the 'T' is uphill, there will be
a run back to crankcase of some of the oil that collects in the hose.

HTH.

Len.

big-vee-twin - 25/10/15 at 06:39 PM

You need to remove the PCV and connect the crankcase to an oil catch tank, can do the same with cam breather too.

SJ - 25/10/15 at 07:59 PM

quote:

Text if I were to connect to the air filter would this not just make a mess in the air filter as I would be introducing the crank case vapours before the air and fuel are mixed.


This is how all the carbed production cars I've ever had have been connected up.

Stu

windy - 26/10/15 at 08:31 AM

Thanks Gents for your replies, I will follow your advice, although tbh I still do not understand the process involved.

Regards Pete.

Paul Turner - 26/10/15 at 12:03 PM

All carb engine production cars I owned in the past simply put the crank case vapours into the air filter. Most put rocker cover vapours strait to atmosphere.

BUT

on both my Sevens with X-Flows and Zetecs I have piped both the cam/rocker cover and crankcase breathers (with valves removed) to a plastic bottle.

Its a simple solution (worked for 26 years with no issues) and complies with circuit regs should you decide to do trackdays. Excess oil vapour in the fuel mixture can cause detonation which is not desirable.

Why complicate matters.