Don`t forget that I am looking for a solution for a Type 4 lump though

Although this still may help others with a Type 1 lump too   

from memory our 1700 T2 van which had twin solex carbs  fitted used an oil bath filter,I assume oil attracts oil so reduces the amount in the induction air.

have a look at rally and motorsport breather systems as they are not allowed to drop oil.

I will try and get photos of mine tomorrow for you

I'm just gonna put a drawing up and pics of mine. Mine is a bit elaborate but get results.

Imagine this. I have twin 34ict's. Rockers are vented both sides. Oil filler has the breather connection on it. I have that 6 entry breather box, 4 in and 2 out. Also a 1/2 litre catch tank.

I dont know if it effects the running. Never had a problem.

So here goes, 2 pipes of the rocker covers (1 each side) routed to the breather box. Breather has 3 unions either side. Top 2 are outlets. Bottom 4 are inlets.





Rocker pipes go to the 2 middle inlets.

Next the line from the oil filler neck routes to the catch tank, which is the lowest point. Pipe in and one out. The out pipe goes to the bottom inlet. Catch tank behind the pipes



The breather box has a gauze between the top outlets and the bottom 4. This causes the vapours to condense and run back down to the catch tank. The catch tank gets emptied about every 600+ miles and produces a water oil mix as a result. normally about half a tea cup full.



Obviously the top 2 goes to the filters. No problems with crud or kak on my venturies.

Ditto!

"OK, I'll have to confess to still running a dump pipe on my buggy engine (improvements are on the 'to do' list)"

Thanks for those pictures Dave, that certainly is elaborate, but I can understand perfectly how that works - brilliant   

On the other bits Dave, I dont get no probs with air movement.

I just figure that the air in the crankcase and heads is swirling and moving so much that it needs to be sucked out in a fashion. There's still plenty in there. The way I look at it is that maybe with that equalisation inside the engine it may help seals stay in place that otherwise get blown out over time. Also may help air drag on engine internals.

But this is not proven and only speculative but the vapour/moisture removal is guaranteed.

Thought I would do an update on this, as have experimented with a few surprising results

I have kept the breathing system relatively simple for now - because the engine is currently in really good shape, I`m not too concerned about an oil catch tank just yet, and am looking primarily at using the breather in the way it was also intended, and that is for making sure that any unwanted gases and fumes from the breather are correctly burnt off - nothing to do with being green, just thought it seemed a good idea.

My breather outlet from the crankcase comes out on a hose, and exits via a T-Piece to both of the carbs so that there is no imbalance etc, they both get the same amount of gasses into them.

I connected the hoses to the tops of both air filters, pretty much the same way that Andy Robinson has done, and Dave Dream has done in the pictures, with the outlet of the hose pointing downwards and directly into the venturi of the carb. Now whilst I fully accept that my engine has not yet been set up correctly, my initial spin around the block when giving it some beans showed a slight spluttering and a touch of rough running. As expected on a near maiden run. Not severe, not bad, and you could certainly live with it - however, disconnecting the crankcase breather pipe resulted in a significantly smoother pick up and also maintaining speed. This got me thinking.

Looking at the old Weber filter I had, and various el-cruddy pancake filters kicking about, they all have a small inlet pipe at the bottom of the filter that pointed the hose in an upwards direction, alongside the main venturi instead of into it. So, I replaced the filters and connected the hoses up in this configuration, and it ran smoothly - in fact, no difference to whether the hoses were connected or not. Conclusion - it works.

So, it would appear that directing a breather hose directly down the barrel of a carb may not actually be the best thing to do   

Any thoughts?

I would think that having it point directly in to the Venturi as it was prior to swapping, would affect the air fuel ratio. Possibly making it leaner or even suffocating it as it's not oxygen it's pulling in but contaminated air from your case and reducing the fuel burn in the cylinders.
Just a thought mind, could be complete bunkum though.

I`m going with contamination too - we "know" that the there are "gasses" that need to be burnt off, so I`m also presuming that they may not burn as well as oxygen.

Food for thought though   

give it a try both ways and see what the difference is if any