Joe Curry wrote:
> > All this talk about crankcase pressure
> > relief has me wondering. I just finished
> > a rebuild and added an electric fuel pump.
> > I also added the vent pipe from the fuel
> > pump opening. I still have the vent hose
> > from the valve cover running into the HS-4's
> > like a stock configuration. Should I do away with
> > these vent hoses? Thanks!
>
> Unless you see oil venting into the carbs it probably won't heur
> to leave it as is.
I wouldn't leave it as is, because technically
that creates a "short circuit", an air leak for
the intake system via the block.
The vacuum in the HS-4s is supposed to suck any
excess crankcase pressure from the block, so there
is always a little vacuum on it and a bit of air
flow through the hose.
However, the block should be sealed, so the only
air it sucks in is blowby from the rings. There really
isn't a lot of flow in the pipe.
If you also have an open air vent from the block
at the fuel pump cover, then air is free to enter
and leave the block at will.
So the vacuum on the carb might suck air
constantly in the vent, through the crankcase, through
the head, through the valve cover, and into the carbs. ie: an
air leak that might show up as being a bit hard to tune out,
because you'd need to richen up to get a decent mix at
idle.
I don't understand why the 1500 needs a crankcase
vent, the existing system works great, doesn't vent
your oily gunk into the air, costs you no
horsepower, doesn't have a catch tank you have
to empty, won't drip oil on your driveway, and so
on.
Not much to improve on really, why change it? Leave
the vent hose system in place.
--
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
"200 channels, and nothing but cats." - Jasper
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