Rover V8 breathing

[AM400]

I,m looking at replacing the EFI breather on the right hand rocker cover on my 400SE with an aftermarket one. Is there anything to be gained by increasing the diameter of the hole in the current breather which is little more than a pin hole! the left hand cover has the large flame trap fitted so why such a small hole on the opposite side?

Cheers

[wedg1e]

The breather has to be small because otherwise air would be drawn through the crankcase and into the plenum chamber (through the flame trap) that hadn't been through the airflow meter, thus weakening the mixture and... well the rest is obvious.

Ian

[AM400]

Ahhh I see Cheers Wedg1e

Andy

[Boosted Ls1]

It also keeps the crankcase in a state of vacuum which should help a bit with minor oil leaks

[pitsnow]

I was wondering if my RV8 suffers any adverse effect since the flame trap is just connected to a hose. The hose is left to ambient air and is not connected to the intake manifold vacuum port. The same applies for the small connection on the right hand side.
Can you guys see any problem with not having a vacuum connection on the rocker cover?

Cheers
Peter

[greenv8s]

pitsnow said:

I was wondering if my RV8 suffers any adverse effect since the flame trap is just connected to a hose. The hose is left to ambient air and is not connected to the intake manifold vacuum port.

It's quite common to connect the vent pipe into a catch tank rather than suck it back into the inlet manifold, I think production cars have to put this through the engine to meet emissions requirements, but the engine itself doesn't much care what you do with it.

pitsnow said:

The same applies for the small connection on the right hand side. Can you guys see any problem with not having a vacuum connection on the rocker cover? Cheers Peter

The small tapping is used to connect the breather to vacuum under part throttle, the breather doesn't need this. But if you leave it disconnected you need to ensure the port on the throttle body isn't left open to atmosphere.

[AM400]

So going back to my original question, is it ok to replace the black plastic housing and foam filter for something more pleasing on the eye so long as I keep the original tube in place, or will the increased filter size and the fact it will be exposed all round and not just through the top like the original cause any problems?

Cheers

[wedg1e]

AM400 said:

So going back to my original question, is it ok to replace the black plastic housing and foam filter for something more pleasing on the eye so long as I keep the original tube in place, or will the increased filter size and the fact it will be exposed all round and not just through the top like the original cause any problems? Cheers

Yes

No

Ian

[GreenV8S]

The size of the vent is not critical. At part throttle the breather is sucked out of the crank case through a small restrictive pipe to the throttle assembly. The flow is regulated by this pipe and not by the crank case breather. At wider throttle openings where there is no significant manifold depression there is no flow through this small pipe but the breather flows through the large diameter pipe routed (normally) to the air filter or some other location upstream of the air flow meter. In either case the amount of unmetered air can be ignored.

[AM400]

Thanks for the advise all.

Andy