spridgets
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Re: Dynos

To: <spridgets@autox.team.net>
Subject: Re: Dynos
Date: Sun, 2 Apr 2000 09:07:58 -0400
References: <20000402124046.12959.qmail@web3806.mail.yahoo.com>
I think you're probably right, but I thought I had heard of some states
"rollers" could be used as dynos.  NJ perhaps?  Just a guess.  Anyone?

Geoff Branch '74 Meejit
----- Original Message -----
From John Holliday <fprodget at yahoo.com>
To: Geoff Branch <branch@valinet.com>; <Daniel1312@aol.com>;
<spridgets@autox.team.net>
Sent: Sunday, April 02, 2000 8:40 AM
Subject: Re: Weber DCOE 45


> I think emmissions dynos are not full fledged dynos. I
> believe they simply put drag on the drive train ti
> simulate road driving conditions.
>
> John Holliday
> 67 Fprod street sprite
>
> --- Geoff Branch <branch@valinet.com> wrote:
> > I think we don't use dynos around here because I for
> > one don't even know where
> > there IS one.   We just started a new inspection
> > system in Massachusetts that
> > requires the stations to use dynos, but when I asked
> > the guy if I could rent
> > some time he said he didn't think the Meejit would
> > fit (didn't have to go on for
> > emmisions because of advanced age) and even if it
> > did, he wouldn't know what to
> > do with the dyno.  I quess it's just programmed for
> > the emissions tests.
> > Anyway.......
> >
> > Here are the specs on my 45 DCOE.  Car is '74
> > 1275cc.  Don't know about any cam
> > work.  Mallory dual point dizzy.  No vacuum advance.
> >  Timing set at approx. 22
> > deg. BTDC.
> >
> > Air Corrector: 175
> > Emulsion tube: F2
> > Main Jet: 125
> >
> > Idle Jet:  45 F 9  (have also used a 50F9; made
> > little difference)
> >
> > Accelerator pump jet:  50
> >
> > Float needle valve: 225
> >
> > Main venturi: 34
> > Aux. venturi: 35
> >
> > 16MM air horns with a K&N filter
> >
> > Richening device blocked with grub screw (took me a
> > while to figure what that
> > term meant!)
> >
> > Let me know what you think.  Should we be doing this
> > off the list?  Anyone mind?
> >
> > Geoff Branch  '74 Meejit
> > ----- Original Message -----
> > From: <Daniel1312@aol.com>
> > To: <branch@valinet.com>; <spridgets@autox.team.net>
> > Sent: Saturday, April 01, 2000 4:51 PM
> > Subject: Re: Weber DCOE 45
> >
> >
> > > Geoff,
> > >
> > > I have the Hammill book who incidentally has an SU
> > book out as well
> > > (veloce.co.uk) - is it any good, has anyone bought
> > a copy?
> > >
> > > The David Vizard book is a real good source of
> > info on calibrating the DCOE
> > > and it was written specifically for the A-Series
> > engine.  It takes out the
> > > trial and error but as far as cost goes it is
> > worth spending the money on
> > > calibration otherwise it was a waste of money
> > spend on the carb in the first
> > > place.
> > >
> > > Can't understand why no-one in the USA ever uses a
> > chassis dyno.  Sure it
> > > costs but I bet you would get your money back in
> > gas mileage savings within a
> > > year (make that a month in the UK).
> > >
> > > Daniel1312
> > >
> > >
> > > In a message dated 01/04/00 21:33:26 GMT Daylight
> > Time, branch@valinet.com
> > > writes:
> > >
> > > << Daniel:  Thanks for the beginings.  I have a
> > Weber book by Pat Braden and
> > > one by
> > >  Des Hammill.  Both are interesting, but actually
> > not that helpful because:
> > > 1. I
> > >  don't have a dyno and 2.  It seems that jetting
> > is mostly a trial and error
> > >  affair that involves 15-20 bucks a pop (8-12
> > British Pounds Sterling, I
> > > think).
> > >  I had all the venturi/jet info written down
> > somewhere...now will have to take
> > >  carb apart again to regain that info.  I'll send
> > it to you when I do that.
> > >  Meejit's down while I wait for a water pump and
> > alternator anyway.  Thanks
> > >  again.
> > >
> > >  Geoff Branch '74 Meejit
> > >  ----- Original Message -----
> > >  From: <Daniel1312@aol.com>
> > >  To: <branch@valinet.com>;
> > <spridgets@autox.team.net>
> > >  Sent: Saturday, April 01, 2000 3:13 PM
> > >  Subject: Re: Weber DCOE 45
> > >
> > >
> > >  > Geoff,
> > >  >
> > >  > I assume you mean the jet inspection cover was
> > missing when you refer to
> > > the
> > >  > Micky Mouse hat.
> > >  >
> > >  > You need a short lesson in how the DCOE works.
> > >  >
> > >  > The engine via the DCOE draws air into the
> > inlet manifold and induction
> > > tract
> > >  > in two distinct places.  The first is round
> > hole about the size of a dime
> > >  > that is on side of the carb (left hand as you
> > look at the carb) above the
> > > l/h
> > >  > barrel (a good book or photo might help).  This
> > hole is used to draw are
> > > into
> > >  > the carb body, more of which later.
> > >  >
> > >  > The engine gets the rest of its air through the
> > carb barrels.
> > >  >
> > >  > If the carb is correctly calibrated (like on a
> > chassis dyno) and the jet
> > >  > inspection cover comes loose or is missing
> > (lost) the engine will run
> > > rough,
> > >  > particularly so in mid range rpm (long time
> > since that happened to me but I
> > >  > think it is the 2,500 to 3,800 rpm range).  At
> > higher rpm there does not
> > > seem
> > >  > to be a problem.
> > >  >
> > >  > Back to the dime size hole.  If you remove the
> > carb top cover complete you
> > >  > will see that the hole leads up to the top
> > cover resticted by the top cover
> > >  > gasket such that it gets to the area underneath
> > the jet inspection cover.
> > >  > This air is drawn into the gallaries that feed
> > the emulsion tubes with air.
> > >  > It is this air that is mixed with fuel drawn up
> > in the jet (idle or main
> > >  > depending on rpm) that is subsequently drawn
> > into the air flow from the
> > >  > barrels that is subsequently further
> > emulsified.
> > >  >
> > >  > If the jet inspection cover is missing then air
> > is either drawn into the
> > >  > emulsion tubes/holes in greater quantity than
> > would be the case when air is
> > >  > drawn in only by the dime sized holes OR... air
> > is drawn in a lesser
> > > quantity
> > >  > by virtue of a weaker vacuum.  To be honest I
> > don't know which it is.
> > >  >
> > >  > BUT
> > >  >
> > >  > Either the mixture leaving the jets (via the
> > progression holes or aux
> > > venturi
> > >  > is richer or it is weaker.
> > >  >
> > >  > SO
> > >  >
> > >  > Obviously your car is not correctly calibrated
> > at some point in the rpm
> > > range
> > >  > but I cannot say whether it is too rich, weak
> > or just poorly emulsified.
> > >  >
> > >  > However, if you provided a spec of the engine
> > along with FULL details of
> > > the
> > >  > calibration of the carb I ought to be able to
> > guess and along the way add
> > > to
> > >  > my knowledge of how the carb works (eg missing
> > jet inspection cover leans/
> > > or
> > >  > richens mixture to detriment).
> > >  >
> > >  > Finally, the jet inspection cover is there for
> > a purpose (eg unfiltered air
> > >  > enters directly into the jet system without it)
> > so buy a new one
> >
> === message truncated ===
>
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