Joe Curry wrote:
> > 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.
>
> In theory it should work that way. But in practical application it does
> not.
Literally hundreds of millions of cars sold worldwide
use similar systems for crankcase venting, including to this
day. (most modern cars have a one way valve called a PCV
valve in the line, that's the only real change)
Logically, I'm going to have to beleive that at
least somebody beleives the system works in practical
applications. You don't see new cars puffing oil out
of their dipstick holes until somebody drills a hole
and hangs a jar down there!
> 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.
I think this is highly unlikely, because the amount of air
flow actually required is VERY low. Again, plug your vent and
hold your hand over the oil filler and you'll feel. Unless
your engine is REALLY knackered and blowing-by like crazy,
the airflow is very low.
The factory emissions tubing actually contains what is called
a "restrictor" in the vent line, which is a fancy way of
saying a plug. It's a white plastic thing shaped like
a thimble that you put over the valve cover vent and
then slide the hose over it.
This plug closes off most of the 1/2 inch hose except
for a pinhole down the middle.
All of the air required to vent the crankcase passes
through this little pinhole comfortably, it's really
not much. You would certainly have no trouble getting
that much air through the pushrod tubes.
Compared to the amount of air that the carbs are
gulping in to run the engine, it's basically
an irrelevent trickle.
> 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!!
Well, it depends how you define success really.
An equally "successful" fix would just be to leave
the oil filler cap off all the time. That would save
you the trouble of having the jar, but still, the
question would be "why would you want to".
--
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
"You can't crush cars with a university degree."
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