Hi Paul
Checked for leaks last night, don't seem to be able to find any...
Took the manifolds of, and replaced with some gasket sealer, still the
same..
900rpm idle when cold, 1400 when hot..
Was thinking, surely a leak on the manifold side of the carb would lead
to rough running (too lean a mixture)...
Would this lead to an inability to lower the idle, even with the
throttle stops wound out..?
I tried puting a little pressure on the throttle spindles to close them
a little (finger pressure only) and this droped the idle to 1100 rpm.
Could there be too much air leaking around the throttle discs?
My other thought is that the springs on the linkage are essentially
loose at closed throttle, should they be exerting more force to close
the throttle, or do you just rely on the springs attached to the
throttle shaft itself?
Cheers for any help
Tim
Paul Tegler wrote:
> it's the equivalent of having individually adjustable
> F/A settings for each throat. It lets you control the
> absolute
> ratio from barrel to barrel on the carb for matching
> purposes.
>
> Paul Tegler ptegler@cablespeed.com
> www.teglerizer.com
>
> ----- Original Message -----
> From: "T. .R. Dafforn" <td214@cam.ac.uk>
> To: <ptegler@cablespeed.com>
> Sent: Monday, October 01, 2001 8:56 AM
> Subject: Re: Weber DCOEs
>
> > Thanks Paul..
> > I'll have a look tonight..
> > Cheers
> > Tim
> > PS the only other bit that confuses me is the Air bypass
> screw...
> > Any ideas on its function?
> > Cheers
> > Tim
> > Paul Tegler wrote:
> >
> > > Ex Valve is another term I see used for the 'back bleed'
> > > valve. The accel. pump and Back Bleed (Ex Valve) work
> > > together
> > > to control the volume and duration of the accel pump
> blast.
> > >
> > > Right behind the idle mixture screw on top, is two
> little
> > > brass
> > > screws (port covers over the progression holes)
> > > With engine off, you're suppose to be able to set the
> idle
> > > stop
> > > by visually setting the position of the throttle plate
> as
> > > visible
> > > down through these screw covered ports.
> > >
> > > If you're idle won't come down.... more than likely you
> have
> > > a
> > > vacuum leak somewhere that is letting air in, raising
> the
> > > idle
> > > speed.
> > >
> > > Paul Tegler ptegler@cablespeed.com
> > > www.teglerizer.com
> > >
> > > ----- Original Message -----
> > > From: "T. .R. Dafforn" <td214@cam.ac.uk>
> > > To: <ptegler@cablespeed.com>
> > > Sent: Monday, October 01, 2001 7:40 AM
> > > Subject: Re: Weber DCOEs
> > >
> > > > Hi Paul,
> > > > Thanks for the reply...
> > > > The problem is the throttle stop screws, backed right
> out
> > > I still get
> > > > 1300rpm...
> > > > I am using a colourtune for the mixture screws, and
> this
> > > seems OK, its
> > > > just I need to get the revs down to sort out the
> mixture
> > > properly, and
> > > > to drive it!!
> > > > Any thoughts?
> > > > Its almost as if the butterflies are not closing fully
> > > perhaps?
> > > > BTW what does Ex Valve refer to?
> > > > I've not seem it mentioned in the Weber book I have...
> > > > Thanks for any help
> > > > Cheers
> > > > Tim
> > > > Paul Tegler wrote:
> > > >
> > > > > Are you referring to the idle mixture screws on top
> > > > > near the manifold ..... or the throttle stop screws
> on
> > > > > the side when you say you have the screws
> > > > > backed out.?
> > > > >
> > > > > ...the following is taken directly from
> > > > > http://www.teglerizer.com/dcoe/webertune.htm
> > > > >
> > > > > Finally, set your idle mixture. Maximize RPM
> with
> > > the
> > > > > idle mixture screws, then reduce idle speed to
> 850-1000
> > > > > (lowest smooth idle speed) with the idle speed
> > > adjustment
> > > > > screw. Tweak the idle mixture screws again at this
> > > speed.
> > > > > Repeat until no further idle speed increase is
> observed.
> > > > >
> > > > > Your idle adjustment screws should be 1-1/2 to
> 2-1/2
> > > turns
> > > > > out from full lean. If they are far outside this
> range,
> > > your
> > > > > idle fuel jet is the wrong size. Increase jet size
> to
> > > reduce
> > > > > the number of turns, decrease jet size to increase
> the
> > > > > number of turns out from full lean (all the way
> > > clockwise).
> > > > >
> > > > > Paul Tegler ptegler@cablespeed.com
> > > > > www.teglerizer.com
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "T. .R. Dafforn" <td214@cam.ac.uk>
> > > > > To: "Paul Tegler" <ptegler@cablespeed.com>;
> "spitfires"
> > > > > <spitfires@autox.team.net>
> > > > > Sent: Monday, October 01, 2001 4:25 AM
> > > > > Subject: Weber DCOEs
> > > > >
> > > > > > Hi Paul,
> > > > > > Judging by your website you seem to know something
> > > about
> > > > > Weber DCOE's on
> > > > > > spitfires..
> > > > > > I have just put a pair of DCOE40 18 on my 1500
> (sports
> > > > > manifold and twin
> > > > > > exhaust, otherwise stock)..
> > > > > > The original jeting for the carbs was for racing
> spit,
> > > and
> > > > > very
> > > > > > extreme...
> > > > > > Even with these the car idled smoothly (800rpm
> cold)
> > > but
> > > > > backing off the
> > > > > > throttle screws as far as they went only allowed
> idle
> > > at
> > > > > 1500 when warm
> > > > > > (not great)
> > > > > > also had no power at less than 3000 revs.
> > > > > > I felt none of this was surprising considering the
> > > jeting
> > > > > > So I rejetted as per the triumph tune suggestions
> for
> > > a
> > > > > mild road mod
> > > > > > car.
> > > > > > Quite a difference, wicked acceleration above
> 2000rpm
> > > > > (warp drive
> > > > > > compared to the SUs, and lovely induction noise!),
> > > > > reaching 4500rpm
> > > > > > almost too quickly in 3rd gear...
> > > > > > Only trouble is that is still refuses to idle
> lower
> > > than
> > > > > 1300rpm dispite
> > > > > > the having the throttle screws turned right out.
> > > > > > Any ideas?
> > > > > > I have, of course, forgotten the jet specs today,
> but
> > > I'll
> > > > > bring them in
> > > > > > tomorrow
> > > > > > Cheers
> > > > > > Tim
> > > > > >
> > > > > > --
> > > > > > Tim Dafforn
> > > > > > University of Cambridge
> > > > > > Structural Medicine Unit
> > > > > > Cambridge Institute for Medical Research
> > > > > > Hills Rd, Cambridge CB2 2XY.
> > > > > > UK
> > > > > > Tel. (01223) 763230
> > > > > > Fax. (01223) 336827
> > > > > > http://smokeroom.cimr.cam.ac.uk/
> > > > > >
> > > > > >
> > > > > >
> > > >
> > > > --
> > > > Tim Dafforn
> > > > University of Cambridge
> > > > Structural Medicine Unit
> > > > Cambridge Institute for Medical Research
> > > > Hills Rd, Cambridge CB2 2XY.
> > > > UK
> > > > Tel. (01223) 763230
> > > > Fax. (01223) 336827
> > > > http://smokeroom.cimr.cam.ac.uk/
> > > >
> > > >
> > > >
> >
> > --
> > Tim Dafforn
> > University of Cambridge
> > Structural Medicine Unit
> > Cambridge Institute for Medical Research
> > Hills Rd, Cambridge CB2 2XY.
> > UK
> > Tel. (01223) 763230
> > Fax. (01223) 336827
> > http://smokeroom.cimr.cam.ac.uk/
> >
> >
> >
--
Tim Dafforn
University of Cambridge
Structural Medicine Unit
Cambridge Institute for Medical Research
Hills Rd, Cambridge CB2 2XY.
UK
Tel. (01223) 763230
Fax. (01223) 336827
http://smokeroom.cimr.cam.ac.uk/
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