5tox

why do people vent the rocker cover on a cossie, it seems a popular thing to do but are there actually any benefits in it?

i mean the pipe that goes from the back right corner to an oil catch tank

LukeDaisley

iTrader: (1)

it releases the pressure/vac of the moving parts and stuff. lol

fraser9764

iTrader: (3)

im sure Harvey/SCS said it wasnt necessary in a previous thread, and some people have had problems with them sucking the oil out of the head.
there shouldnt be any excess pressure up there anyway as the pressure is generated by piston blow-by.
my new engine will be breathing from both sides of the block and returning to sump, or catch tank, not decided just yet.

ajamesc

if it was good enough for the rs500 touring cars its good enough for me lol plus cosworth must have thought it needed it or the hole wouldent be there but i see some dont

BRAMMER

iTrader: (23)

This seems to be the most confusing topic in the Cosworth world - i'm fitting my 5 port system up to the cam cover, inlet side, retrun exhaust side (not sump), 2x catch tank - some say it's wrong but it's been proven on +500bhp cars so it's good enough for me.

Mr RS500

iTrader: (6)

You will always get various opinions about this issue

But as said , if this way was good enough for the touring cars then its good enough for mine


The one at the back of the rocker cover actually vents the crank case not the head

Miller 3

iTrader: (4)

Come on Pauline you should know better... see above mate lol

Mr RS500

iTrader: (6)

I dont get your point

pee vee

think it was a cam cover / rocker cover slip up..

5tox

I dont think the hole is there on a standard engine, i think half have just been modified to accomodate the breather hence why an untouched one sells for so much

... i could be wrong though, its just my understanding

5tox

thinking about it, i do agree with the above statement that the pressure would be caused by blowby gasses so on a fresh healthy engine it shouldnt be an issue,
think ill leave mine as it is since its getting a rebuild after classic ford this june

ajamesc

its there on all of them u just have to drill the blank out

tabetha

As said there on all of them, if it's good enough for a RS500 race car!!, this bears little relationship to the road cars.
It doesn't matter how fresh newly built any engine is, they will ALL have blowby, even non turbo cars have blowby, that's how the oil gets contaminated!!
There will be pressure present in the r/c, as pressure will always seek the path of least resistance, the hole being a large drain hole return for the oil will have pressure, so this can be relieved by a breather, whether you need one depends on a lot of things, boost pressure being one, but even on a bog std cossie the breather system was marginal at best imo.
There are some theories that breathing from here would stop the oil flowing back, clearly this isn't and can't be the case, as the head would fill with oil starving the engine, and they don't.
I'm building my breather at the mo, from block both sides, r/c, and sump on off side, but instead of the useless tanks containing nothing but air, these will be filled with stainless wool, actually scrub buds so allowing air passage but not oil droplets.
Just my view.
tabetha

fezzajsy

iTrader: (9)

anyone know what pipe size baileys breathers need?need to do mine braided

mattman1234

I have my own theory on this,,,,,,,,take a plastic bottle(this is the space under the rocker cover).Fill it with water(the oil),turn it upside down,the water(oil) drains/glugs out of the lid.Now do the same again but make a hole in the top of the bottle(actually the bottom).This hole would represent a breather in the top of the head.Now see how quick the water(oil) drains out.

pikachu

i thought most cars had this? not all going into a container though.

i was always told its a vac release for pressure that builds up in the rocker cover from the cams spinning.

even my fiesta has one i think, that filter just above my inlet mani above the fuel line is a vac release filter. it hisses when i turn the engine off for about 3 seconds.

whizzisat114

iTrader: (2)

i think all engines produce crank case compression and the breather systems help release this as it would start blowing gaskets
id of thought big psi car's would need to vent this pressure off also

5tox

i saw a thread before tab where you mentioned using wire wool / scrub buds, gonna copy that idea as it makes sense... otherwise the mixture of oil/air would just escape from the breather before being seperated

Ridgey

iTrader: (5)

Good idea as it was designed like that, that is why there is the port through the head that the cam cover seals around and you can drill the top out to access it.

miller3 i didn't get your point either