Ince the original Jubilee crankcase breather is not the best design I made an upgrade to it.
I bought a 9mm brass hose connector at a local store for hydraulics etc. They kindly lent me the 1/2 inch tap and the correspondending drill for it.
I marked the position of the new outlet for the crankcase breather, drilled the hole and used the tap for the thread.
The original outlet seen under the new connector will be blocked.
I will also use this VACO one way valve in the hose which already works well on my Navigator.
The breather mod was already done on the Navi when I got it.
Pipe fitting.
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Breathing
"I am an advocate of extra breathers, but on a well sealed engine a one-way valve could cause a vacuum on the up stroke"
Hi Richard,
This is precisely what you need!
Think about it and the valve is self limiting. Once there is a lower pressure in the crankcase, no more air/gas/oil mist can be expelled as the valve will stay shut. It is doing what the 'Maltese Cross' breather found on all Dominator camshafts was trying to do, but far better.
Regards,
George
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Breathers x 2.
Hi George/Ulrich,
With a parallel twin or single you might need 2 breathers with one way valves, one out for the down stroke and one in for the up stroke. With a 180 degree crank the alternating pistons cancel out the pumping action, and the same applies for an in-line 4. Having said that, you still need a breather to cope with piston blow-by.
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Sorry Richard
But you WANT a lower pressure in the crankcases. No need to let air in at all on our old clunkers. As I said earlier, the timed breather on the cam let's gas out on the down stroke but is shut on the up stroke to try and keep a lower than atmospheric pressure in the engine. A reed type valve like Uli is installing does the same job as the timed breather but does it better as it can vent out whenever the pressure inside is greater than the outside. Low c/case pressure means less oil leaks and lower pumping losses to name but 2 benefits without any downsides.
For cars in Europe, since the early 1980's and emission rules it has been a legal requirement that the engines internal/crankcase pressure must be lower than atmospheric when the engine is running.
Regards,
George
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Crankcase Breathers
Yes - a vacuum under the pistons is good - it will have the effect of not pushing oil out... which is of course, the cause of oil leaks.
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Hi Ulrich,
The size of these is 1/4 inch BSP, which is the nominal bore size of British Standard Pipe fittings, but varios bore sizes are available. The tapping size drill bit should be 29/64 inch, but 11.5mm is virtually the the same.
I am an advocate of extra breathers, but on a well sealed engine a one-way valve could cause a vacuum on the up stroke.