Trevor in his typical fashion proclaimed:
> Joe Curry wrote:
>>> If you have the vent hose from the valve cover,
>>> then you can block off the vent pipe at the
>>> fuel pump opening. Then you have a working closed
>>> system.
>>
>> Yes, YOu will have a closed system that will blow oil out the >> Dipstick
Tube!!!
>
> No.
> You blow oil out of the dipstick hole if your engine
> has no venting at all, because there is nowhere for
> the pressure to go, and it finds someplace.
>
> When you have a proper vent hose from the valve
> cover (as stated above) then that is where the pressure
> is safely released.
>
> Excess pressure in the crankcase is drawn out of here
> by the vacuum in the carb body, then pulled through the
> carbs and through the engine.
>
> That's what it's for, it all works just fine.
Trevor,
In theory it should work that way. But in practical application it does
not. Been there, done that! My suspicion is that the pushrod tube channels
are not sufficiently large to allow all the built up pressure to work its
way up to the valve cover and vent through the valve cover vent. The vent
in the lower end of the engine does in fact stop the venting through the
dipstick tube.
Some carb bodies may in fact create enough vacuum to allow the pressure to
be vented, but this whole thread started in relation to Weber DGV carbs
which apparently are not among those particular carbs. My own application
started with a single DCOE (which I don't recommend to my worst enemy) and
was swapped out for a pair of 1.25 SUs. The SU's don't have any provision
for connection to the venting system. So necessity being the mother of
invention, I got inventive and that is what I came up with.
And believe it or don't, It really does work!!
Joe
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