How much pressure does the engine develop ?
By what I'm looking at and reading it might be a bunch.
This may be a fix to my spotting problem on the driveway.
The 71 runs like a sewing machine but pushes that little bit of oil.
I'm going to dump the works to a jug !
Screw the carb hose !
-----Original Message-----
From: Joe Curry [mailto:spitlist@gte.net]
Sent: Friday, March 30, 2001 7:29 PM
To: Craig Smith
Cc: 'Trevor Boicey'; Larry Elswick; Spitfires mailing list
Subject: Re: 1500 Venting
Craig (and all),
I came to all my conclusions about Spit 1500 oil blowby from personal
experience. Not needing any emissions stuff on a Mk1 (where my 1500 engine
resides), I found no need to put all that heavy and restrictive stuff on the
engine. I too was the unwitting recipient of the infamous "dipstick
stream".
My fix was to study the Mk1 engine and essentially duplicate what was done
there. Since there was a vent on the right side of the 1147 engine
(covered in later models), I had to find another place to vent the crankcase
directly. Having already installed an electric fuel pump, the pump hole
was the logical place to vent the engine. Putting a Tee connector onto the
valve cover vent and connecting the two hoses together allowed me to stuff
only one hose into a catch bottle.
Incidently, I have not gotten much in the way of oil into the bottle, and
none out the dipstick tube since making the modification. So I guess it
works!
Joe
Craig Smith wrote:
>
> Let me tell you what I got,,,,
>
> 71, that leaks inside the drivers side motor mount.
> I'm wondering if the following will stop it. It only happens when I stand
on
> it anyway.
>
> The venting that I have is from the valve cover to a Tee, one goes to the
> carbon canister the other goes to the Stromberg.
> The one to the Stromberg has a kink cause I tried to take a piece of
heater
> hose to make the run. It's too short, so I get a kink.
> I don't really use the canister cause the plastic tube from the gas tank
> caught fire when I was welding in the new floor pieces.
> After Joe reminded me to read the other messages I got to thinking, why
not
> do away with the line to the carb and dump ALL of it to a New catch type
jug
> where the carbon thingy sits.
>
> Concourse, list with deductions, I don't care about that stuff !
> Comments ??
>
>
> -----Original Message-----
> From: Trevor Boicey [mailto:tboicey@brit.ca]
> Sent: Friday, March 30, 2001 6:33 PM
> To: Joe Curry
> Cc: Larry Elswick; Spitfires mailing list
> Subject: Re: 1500 Venting
>
> 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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