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Re: Weber DCOE 45

To: branch@valinet.com, spridgets@autox.team.net
Subject: Re: Weber DCOE 45
Date: Sat, 1 Apr 2000 16:51:38 EST
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
 > (aptfast.com) and then get the jetting sorted.
 >
 >
 > Daniel1312
 >
 > PS.  Most books on the DCOE aren't that good but you might find it helpful 
to
 > buy some anyway.
 >
 > In a message dated 01/04/00 18:01:26 GMT Daylight Time, branch@valinet.com
 > writes:
 >
 >
 > << And on another note:  My 1275 had been suffering from a 
hesitation/misfire
 > at
 >  low rpm and high load situations.  Then it went away.  Runs Great!  So I 
went
 >  a-looking for a reason and found the mickey-mouse hat on the Weber was
 >  missing!!!!!  For anyone with  Weber side draft experience then:
 >  1.  Why would this improve the performance of this carb??  And what does 
it
 >  indicate is wrong with it with the hat on?
 >  2.  Should I just leave the damn thing off?
 >   >>
 >
 
 
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