17 replies to this topic

[EasterBern]

Hi All,

 

I'm converting my Mini to twin SU HS2. I'm also converting it to have a brake servo.

 

I need somewhere to connect both the crankcase breather pipe and the servo pipe.

 

I have a manifold, but it's not tapped. It does have what looks to be an area that could be drilled and tapped. But that still leaves me one connection short!

 

Can I put in a t-piece in the pipe for both the servo and the breather, I'd put a valve to the servo to stop it picking up the oil fumes? Or could I just put a filter on the crankcase breather and forget about connecting it to the manifold? And do i need to worry about a flame trap?

 

So many questions!

 

Thanks in advance,

 

Bern.

 

 

 

[nicklouse]

Loads of manifolds available with places for more than one take off.

I would not use a T piece it levels you open to brake failure.

Yes you will still have a one way valve fitted in the self I line.

[Carlos W]

Will the draw of the inlet manifold not b too much for the breather?

[AandR]

when i run my breather to the carb it made the car smoke , crank case pressure is fairly high though so i run a catch tank for the cam cover and clutch cover 

[EasterBern]

Thanks all,

 

I'm pretty certain that the breather originally vented into the manifold, though it was a few weeks ago now that I took it apart.

 

Looking at Mini engines on the net i can see that some people have fitted one of those small filters to the breather, perhaps I'll do that!

 

I guess I could buy another manifold, but I'm trying to keep this on a tight budget and I already have a manifold that I can adapt.

 

Cheers,

 

Bern.

[carbon]

Quite a number of the original twin SU set-ups included a breather pipe going directly into the inlet manifold. But these were always used with a specific type of valve (PCV) which limited the amount of crankcase gases being drawn in to achieve a determined crankcase pressure.

[Spider]

As carbon has said, not at all a good idea to connect the crankcase breather direct to the manifold - it will suck all the oil out if the sump! You will need to use a PCV Valve in between.

 

There should also always be an Oil Separator just where the Breather comes off the crankcase.

[EasterBern]

Doesn't a flame trap also work as a PCV? I think for now I'll not put it into the manifold but use one of those little filters. I can always change it later if necessary. I've got the standard side cover with what I assume is an oil separator attached.

 

Many thanks,

 

Bern.

[Spider]

Doesn't a flame trap also work as a PCV? I think for now I'll not put it into the manifold but use one of those little filters. I can always change it later if necessary. I've got the standard side cover with what I assume is an oil separator attached.

 

Many thanks,

 

Bern.

 

A 'flame trap' isn't and doesn't work like a PCV. Two different bits of kit, though often used together.

 

I gotta say, I've never crazy about just venting the crankcase to the atmosphere, for a few reasons;-

 

The car will tend to smell oily and fumey

The engine will tend to leak oil

It usually doesn't meet emissions stnadads

It will tend to build up moisture in the crankcase, which often shows up as 'mayo'.

[carbon]

Good desription of PCV operation here: http://mgaguru.com/m...ngine/cv103.htm

 

As Moke Spider says, the PCV is very different to a flame trap.

[EasterBern]

Yes, sorry, I do know what a PCV does (I had to change one on an MX5 i once owned), I had wrongly assumed that the flame trap and the PCV were a combined bit of kit!

 

Those are very good points regarding venting to the atmosphere, and you've persuaded me not to do it! I'll have to check where it originally vented, it must have been either into the manifold or maybe the air filter box. The latter I guess wouldn't require a PCV as the vacuum effect would be much less.

 

So what is normal for an A-series with twin carbs? I've had twin carbs on quite a few cars, but never on an A-series.

 

Cheers,

 

Bern.

[nicklouse]

You say normal.

There us no normal in Mini world. But there is likely to be 2 or three ways to do the same thing differently.

Pick one and run with it.

[Spider]

There's a few different types of SUs and Manifolds with various ways of connecting it all up.

 

To minimise what other parts you may need to get a hold of, can you throw up a picture of what you have and we can suggest where to go from there.

[EasterBern]

Yeah, I guess you're right, best way to learn by trial and error!

[EasterBern]

There's a few different types of SUs and Manifolds with various ways of connecting it all up.

 

To minimise what other parts you may need to get a hold of, can you throw up a picture of what you have and we can suggest where to go from there.

Ok, I'll try to do that.

 

I've actually just got a pile of bits at the moment!