Rover Rocker Covers - breathers

[breskit]

On my Rover 3.5 there are two breather pipes coming off the top off the rocker covers, one each side.

On one side is a flame trap that feeds back into the air filter.
On the otherside, I have the oil filler hole plus another small breather that has nothing attached to it.

Whilst working on the timing on Monday I noticed that there is a lot of "stuff" blowing out of this hole, perhaps a cooling vent. Is there supposed to be a pipe or something attached to this and if so where does it go? Does it just redirect this air downwards?

I can see that without something like this, the underside of my bonnet will get very messy indeed.

Thanks,
Tony B

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http://homepage.ntlworld.com/tony.breski

[kev]

The "big one" sucks gas out of the crankcase through a mesh filter gauze. The suction comes from the inlet manifold throught the carb or whatever system you've got. The little tube on the other rocker cover allows air into the crankcases to be sucked out by the other pipe. The different sizes of pipe allow a vaccuum to be built up in the crankcase. The little pipe should have a small sponge filter on it, or similar. The reason you've got gunge coming out of the little pipe is either the mesh filter on the big pipe is blocked or the vaccuum pipe is plumbed into the wrong place and not pulling the vaccuum.

regards
Kev

[breskit]

Kev,

Are you saying that these two pipes should be connected? This would require a sort of Y-shaped hose to do this. I don't understand.

I have a Webber 500 carb and have the larger pipe connected directly to the underside of the air filter (was advised to do it this way). I know that I am better off with a filter between the rocker cover and the air filter, but that's not required right now.

I guess what I don't understand is how the large and the small pipe are connected as they sit on diagonally opposite corners. I'll put a pic up later tonight to show the setup.

Would you have a pic I could check out to see how the plumbing should be setup?

Thanks,
Tony B
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http://homepage.ntlworld.com/tony.breski

[STEVE G]

Tony
On my old Rover covers I welded the small hole up,to no ill effect.My new SBF covers only have one hole in each.One goes via a PCV into the base of the carb the other breathes air into the block.I have seen intalations that connects this one the the base of the air filter so at high revs(when the PVC does not work)the engine breathes thru the air filter.
I have also seen in some catalogues,Deamon Tweeks I think,a small K&N breather that will fit the small pipe on the rear of your covers
Steve G
GRAVETTI 427-Rover 281ci.

[russell_ram]

Tony,

sorry but piping the 'big' rocker vent into the air cleaner will not work. There is never enough vacuum in the air cleaner to 'suck' through the engine.

What you need to do is:

Big pipe goes to the port on the front of your carb, which you will have currently blanked off or ported to brake vacuum, brake vacuum from tapping on front top face of manifold (std rover position). You'll probably need to use a reducer in the pipe to get down to the right diameter..

Small pipe needs a 'K&N' type filter to 'suck' through. If you have a big Halfords superstore they have just the bit in their Ripspeed section.

Russ

[russell_ram]

Check the picture in attachment 2 of reply 23 in Steve G's 'watch this space' thread. It clearly shows the central port in the carb which you should connect the out pipe from your big rocker vent (in this case Steve's shiney billet aluminium equivalent on the front of the LH rocker).

Russ

[kev]

sorry if my explanation was confusing. I think Russ has probably eaplained it, but just to clear it up. The idea behind these pipes is to scavenge the crankcase of polluting gases(so they don't get into the atmosphere) and to provide a little vaccuum in the crankcase. The big pipe normally on the offside rocker is the suction pipe. The inlet manifold provides the suction, so connect it as Russ suggests. THe little pipe provides the air to get into the crankcase. So therefore the air flows into the rocker via the the thin pipe which is open to atmosphere, down the head oilways, into the crankcase, up the other head oilways into the other rocker, through the mesh filter (oil trap) into the big pipe, then manifold where it is sucked into the combustion chamber and any gases are burnt.

What this means is, put a filter on the nearside rocker vent, connect the big pipe to the inlet manifold as Russ outlined.

Kev

[interestedparty]

I would like to add to Russell's reply, that ideally you should inset a PCV valve in the pipe between the flame trap and the PCV valve on the carb (the big one in the middle). The purpose of the valve is to close the pipe during periods of high vacuum, such as when the engine is idling, and then to open when vacuum is present in smaller amounts.
You can get a suitable valve from Real Steel part no BYFV 184 costs about £2 and fits in the neck of the flame trap. Ask for the part by number, they don't know about this trick
I learned the need for the valve when I first ran a Weber 500 with out one, the whole engine whistled, sounded like clutch squeal

John

[Dan]

My block originated from a range rover. Both crank covers are conected to the vacum on the carb via a 'Y' piece, a couple of inline flametraps are present between the case and the 'Y' piece on each side.

sucking the engine (ooo-er) could relieve the engine of it's oil so it has a small tube towards the rear / center just above the gearbox bellhousing that I have remotely attached an airfilter to the end of the hose, to allow air into the engine below where any gasses can get trapped.

This is how it is setup on the range rover, All I did was renew the hoses. If your block has a small hole in the back center then it may be setup in a similar way.

Just to add quickly, The cases are connected to the base of the Carb, Not the airfilter..


Dan ~ http://homepage.ntlworld.com/danny.mann/

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[Dan]

>>the whole engine whistled.

Yes I can vouch for that, Havn't got round to getting the valve fitted yet, but I'm sure it would remedy the mild whistle I'm experiencing.


Dan ~ http://homepage.ntlworld.com/danny.mann/

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