[ROVERNET - UK] Calling Rovernet Brain trust!!!

Fri Sep 29 09:11:17 BST 2006

The float bowl does not supply air - it is only the pressure on top of the
fuel that varies.  Small amounts of air flow in or out to achieve that.
When the vacuum is high at the butterfly, the economiser reduces the
pressure in the float, thus reducing the amount of fuel flowing up the jet.
If it sticks open, the carb would be lean most of the time; the way to test
it is disconnect it from the butterfly region so that the float vents to
atmosphere.

PVS

----- Original Message ----- 
From: "John Burkhard" <burkhaj at earthlink.net>
To: <rovernet at lyris.ccdata.com>
Sent: Friday, September 29, 2006 5:49 PM
Subject: Re: [ROVERNET - UK] Calling Rovernet Brain trust!!!

> Hi Paul,
>
> I got my magnifying glass out and looked more closely at the cutaway
> drawing of the economizer valve in the Wade book.  Just like the S. U. it
> self , it has a piston, needle and a fixed orifice.  Like you Paul, I also
> think that it only works at part throttle. But it looks like the manifold
> pressure is adjusting the volume of vent air going into the float bowl at
> atmospheric pressure.  If the valve was stuck or sticking near the most
> restricted position I would think the engine would idle sort of normal.
> Once the throttle is cracked open the manifold pressure could not open the
> atmospheric pressure vent valve and the engine could not get enough fuel
> and would die.  All this is only what I think.  I was unable to find any
> printed information on the this system in any of the books that I have.
So
> for all of you with a single HD type S. U. on your P5 three liter put this
> system on the things to check from time to time.
> ----- Original Message ----- 
> From: "Paul Smith" <Paul.Smith at auroraenergy.com.au>
> To: <rovernet at lyris.ccdata.com>
> Sent: Thursday, September 28, 2006 7:37 PM
> Subject: RE: [ROVERNET - UK] Calling Rovernet Brain trust!!!
>
>
> SUs are easy, easier than fixed choke carbs.
> The economiser is meant to lean the mixture on cruise by applying some
> vacuum to the float bowl, reducing the pressure feeding the fuel to the
jet
> when the Bernoulli force is applied (via lateral pressure reduction in the
> air stream through the variable venturi, aka under the piston).
> I doubt it will be strong enough to cause Ben's symptoms, but we will see.
> Wait for the next thrilling instalment of "The P5 on PEI vs the Owner."
>
> PVS
>
> -----Original Message-----
> From: rovernet-bounces at lyris.ccdata.com
> [mailto:rovernet-bounces at lyris.ccdata.com]On Behalf Of Kent Kinard
> Sent: Friday, 29 September 2006 12:30 pm
> To: rovernet at lyris.ccdata.com
> Subject: Re: [ROVERNET - UK] Calling Rovernet Brain trust!!!
>
>
> Very interesting...I have much to learn about SU's.  Thank
> you, John.  This may explain some tuning problems with the
> 3L7 in my P4.  I will have to check all the areas
> mentioned.  Rovernet to the rescue again.  Hope some of
> this works for you, Ben.
>
> Rovereeducatedly,
> Kent K.
>
> On Thu, 28 Sep 2006 17:28:56 -0700
>   "John Burkhard" <burkhaj at earthlink.net> wrote:
> > Hi Ben,
> >
> > I have looked at the factory workshop manual, the Wade
> >S. U. book and the P6 shop manual in detail.  I think I
> >may have found the problem(s).  Your car, as do all NADA
> >P5s, has an economizer (Rover term) or weakening device
> >(S.U. term).  This is mounted on top of the float bowl by
> >the center bolt that holds the cover on.  This valve
> >system regulates or controls the float chamber air vent
> >with ported vacuum. One end of the regulator valve has a
> >line going to the top of the SU throttle chamber next to
> >the vacuum advance line to the distributor.  At the other
> >end of the valve there is a hose that goes to the air
> >cleaner elbow at the carburetor.
> >
> > Remove and very carefully disassemble this valve.  There
> >are a few, very small parts in this assembly so try to
> >remember where they all go.  It looks like you will need
> >to soak the valve casting in a good carburetor cleaner
> >and use lots of compressed air to give it a good
> >cleaning.  Let me know how this works.  jb
> >
> >
> > ----- Original Message ----- From: "Ben Rodgers"
> ><irishrover at netscape.ca>
> > To: <rovernet at lyris.ccdata.com>
> > Sent: Thursday, September 28, 2006 11:07 AM
> > Subject: Re: [ROVERNET - UK] Calling Rovernet Brain
> >trust!!!
> >
> >
> >> Hi Guys
> >>            I need help! The Rover has me stumped (1967
> >>P5  Mk3 Std )
> >> The car starts and idles okay with full choke on , but
> >>once underway I
> >> can
> >> hardly get out of second gear and continue to need
> >>choke. >
> >>
> >>
> >>
> >>
> >> FREDERICK  (BEN) RODGERS
> >> born in Belfast, Northern Ireland,
> >> Author of "lily and me" a great book and a great read .
> >> Order on line at amazon.com. Book # ISBN1-55430-019-3
> >>
> >>
> >> _______________________________________________
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> >>
> >
> >
> >
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