I have no idea if the breather put strain on the filter top. Engine builder seemed to think the studs holding the filter top on were a bit thin, i seem to remember them getting changed for some heavier duty ones.
Fuel tank breather. The connector’s one of the blue nylon Tefen ones. I use them on me fuel lines as well. Much neater than brass.
ahh yes of course, mine T's into the main oil breather and then the carb top. Yours seems a much neater and better solution.
I had a bit of time to think about it, but it worked out quite neat. I’ve got two breather hoses, one going to each filter, as I wanted to keep more or less the same area as the VW original, which is quite big. Only disadvantage is that filters get a bit oily over time.
Thinking about one of these and Snotts idea of a grommet. I will investigate the type of filter lids I have, there's no hatch so one will have to be removed.
I have used these with a grommet in the thin tin type ict filter top, and although it works OK, the thick pipe tends to cause the fitting to tip over and look a bit unsightly. If you have thick cast type lids it might hold them upright a bit better.
Well you know I like to be contrary... It's purpose is to relieve the turmoil inside the case caused by two pistons at one end of the case moving out while the two at the other end move in. There are mods you can do inside the case to help the 'air" get from one half of the case to the other. The bigger the capacity the more air. In mine it's 1.2 litres once each direction per rev. Counterbalanced stroker cranks get in the way too. Racers add another crank breather at the flywheel end. Does a little negative pressure help relieve that or is a simple vent good enough? If you think about one end of the case as the pistons are moving inwards, 1.2 litres are pumped into that half of the case in 0.02 seconds at 3,000rpm Personally I can't imagine some negative pressure making much of a mark on that but I'd be happy to be proved wrong.
I hadn't thought/heard about the breather bring there to relieve the movement of air - makes sense. The way the oil leak thing was explained to me was that the helical groove in the outside of the bottom pulley will leak oil, despite the helix "winding" the oil back in, unless the breather is connected and the slight negative pressure is enough to prevent the leak. Is that codswallop?
Except...there is no helical groove on a type-4 pulley and the rotating shaft seals are the far side of bearings from any case pressure. Oil pressure and blocked oil drains maybe. There's one for the space between the flywheel seal and thrust bearing than can be compromised or even blocked by over jealous application of sealant fitting the seal or wrong sealant of the case halves can I think block the drain at the pulley end... I'm going from memory for the drain examples...ready to be shot down but pretty confident. There's another drain on the cam bearing furthest from the gear that is sometimes blocked by fitting the shells in swapped locations...the wider centre shells fit here and block it though that burns the bearing out rather than causing a leak... Oh so many pitfalls await the unwary builder.
I'm pretty sure what you said is what my engine builder told me as well. I have type 1 engine 2110cc. Oil filler neck one pipe downwards vents to atmosphere (road) Oil filler neck one pipe up to large breather box Breather box has pipes to both carbs and pipes to both rocker covers Fuel breather pipe joins into oil breather pipe going to the carb. Think all that is to get negative pressure in the crankcase Hope that helps
I know I'm a trouble seeking doom monger, but unless the downtube also has the rubber "beak" on the end which acts as a one way way (out only) valve, your carb is sucking from that big open pipe too so you won't have the negative pressure or it will be vastly reduced. It's great to have everything in place, but one missing part and... Hopefully, your experienced builder will have fitted it, this is more for general readership. Most I've seen do not have the rubber bit.
So do I connect the crankcase breather on my type 4 to a carb or vent to air with a beak? Wouldn't the beak be counterproductive to the volume of air shifting purpose of the breather?
I don't think it does have any beak on it. I seem to remember sticking my finger up it and im sure its just open to the air.
