[DeTomaso] Stumbeling.

John Taphorn jtaphorn at kingwoodcable.com
Thu Jul 16 20:33:02 EDT 2009


Doug

Your suggestion that he examine the exhaust to see if it is black during 
acceleration is a good one.  My money remains on the scenario that he is 
ridiculously lean and not overly rich.  I've been there recently.

JT
----- Original Message ----- 
From: "Doug Braun" <doug at silicondesigns.com>
To: "gudmund frøland" <gudmundfroiland at yahoo.no>
Cc: "DeTomaso Forum" <detomaso at realbig.com>
Sent: Thursday, July 16, 2009 5:43 PM
Subject: Re: [DeTomaso] Stumbeling.


> Unfortunately, I've never taken apart a Demon carb, only Holleys.  Others 
> on
> the forum know a lot about Demons so hopefully you'll get an answer from
> them.  It likely has a power valve like the one in a Holley, or it may 
> even
> use a Holley power valve but I don't know.  If it does have one like a
> Holley, it should be stamped with a number on it that will tell you at 
> what
> vacuum level it operates.  Above that vacuum level it's closed and below
> that level it's open and richens the mixture.  If it is blown, it will
> richen the mixture all the time which may be your problem.  The most 
> common
> valve is a # 65 which means it operates at 6.5 inches of vacuum.  I'd 
> start
> by replacing the valve with one identical to what's already in there and 
> see
> if it cures your problem.  If you have a very radical camshaft that 
> prevents
> your engine from creating high vacuum values, you could also try a # 45
> valve to see if it cures your problem.
>
> Doug Braun
>
> -----Original Message-----
> From: gudmund frøland [mailto:gudmundfroiland at yahoo.no]
> Sent: Thursday, July 16, 2009 1:51 PM
> To: Doug Braun
> Subject: RE: [DeTomaso] Stumbeling.
>
>
>
> It is a Demon dubblepumper, i never know how it worked from beginning.It`s
> been on the car sence i bought it. The car came from US when i bought 
> it.It
> works fine if start from 0 with full troottle , onley when cruse and give
> full it stuble?
> Best regards    Gudmund Froiland
>
>
> --- Den tor 2009-07-16 skrev Doug Braun <doug at silicondesigns.com>:
>
>> Fra: Doug Braun <doug at silicondesigns.com>
>> Emne: RE: [DeTomaso] Stumbeling.
>> Til: "gudmund frøland" <gudmundfroiland at yahoo.no>
>> Dato: Torsdag 16. juli 2009 19.29
>> I assume this is a Holley carburetor,
>> correct?
>>
>> If so, had this carburetor been running properly on the car
>> and then
>> recently stopped working properly or was it recently
>> installed and has never
>> worked properly?
>>
>> Doug
>>
>> -----Original Message-----
>> From: gudmund frøland [mailto:gudmundfroiland at yahoo.no]
>> Sent: Thursday, July 16, 2009 10:14 AM
>> To: Doug Braun
>> Subject: RE: [DeTomaso] Stumbeling.
>>
>>
>>
>> How can i determen what size powervalve i would need? I
>> understand there are
>> different sizes.
>> Best regards Gudmund Froiland
>>
>>
>> --- Den tor 2009-07-16 skrev Doug Braun <doug at silicondesigns.com>:
>>
>> > Fra: Doug Braun <doug at silicondesigns.com>
>> > Emne: RE: [DeTomaso] Stumbeling.
>> > Til: "gudmund frøland" <gudmundfroiland at yahoo.no>
>> > Kopi: "DeTomaso Forum" <detomaso at realbig.com>
>> > Dato: Torsdag 16. juli 2009 17.31
>> > You could have a bad power valve and
>> > they are so inexpensive you should just
>> > replace it. What may be happening is that your
>> blown
>> > power valve is
>> > constantly providing far too rich of a mixture between
>> off
>> > idle and
>> > upper-mid RPMs. It's not until you get enough RPM
>> up
>> > to bring enough air
>> > through the carb to handle the extra fuel from the
>> power
>> > valve that it
>> > clears out. If you're blowing black smoke while the
>> > engine is stumbling
>> > that's a good clue your power valve is gone. Or
>> > better yet, have someone
>> > follow you when it happens and have them tell you if
>> the
>> > exhaust smells rich
>> > when it happens. Or just replace the valve which
>> may
>> > be the quickest thing
>> > to do. Be sure to buy new bowl and metering block
>> > gaskets before you
>> > disassemble the carb.
>> >
>> > Hope this helps
>> >
>> > Doug
>> >
>> > -----Original Message-----
>> > From: gudmund frøland [mailto:gudmundfroiland at yahoo.no]
>> > Sent: Thursday, July 16, 2009 1:43 AM
>> > To: Doug Braun
>> > Subject: RE: [DeTomaso] Stumbeling.
>> >
>> >
>> >
>> > Thanks. Acc pump are working ok. No play on the
>> cam.Its not
>> > just stumbling
>> > for a second and comming,it works like when i give
>> full
>> > trottle it stuble al
>> > the time until i eaze on trottle, then i can go for
>> it
>> > again more gently and
>> > it pulls ok.I was wondering how that power valve are
>> > working ?
>> > Best regards Gudmund Froiland
>> >
>> >
>> > --- Den tor 2009-07-16 skrev Doug Braun <doug at silicondesigns.com>:
>> >
>> > > Fra: Doug Braun <doug at silicondesigns.com>
>> > > Emne: RE: [DeTomaso] Stumbeling.
>> > > Til: "gudmund frøland" <gudmundfroiland at yahoo.no>
>> > > Dato: Torsdag 16. juli 2009 00.07
>> > > Check that the accelerator pump is
>> > > working.
>> > >
>> > > Doug Braun
>> > > blue 73L #5505
>> > >
>> > > -----Original Message-----
>> > > From: detomaso-bounces at realbig.com
>> > > [mailto:detomaso-bounces at realbig.com]On
>> > > Behalf Of gudmund frøland
>> > > Sent: Wednesday, July 15, 2009 2:50 PM
>> > > To: Detomaso at Realbig. Com
>> > > Subject: [DeTomaso] Stumbeling.
>> > >
>> > > I have been out crusing a little and if i
>> accelerate
>> > with
>> > > full trottle it
>> > > pulls good but if i cruse and give full trottle
>> my
>> > engine
>> > > just stumble and
>> > > wont pull any before i lighten the trottle.When
>> it
>> > start
>> > > pullin i can go for
>> > > it and it pull strong. Are there any good advise
>> here.
>> > No
>> > > pinging so i
>> > > belive the timing is right.
>> > > Pantera 06872 Gudmund Froiland
>> > >
>> > >
>> > >
>> >
>> >
>> >
>> >
>> _________________________________________________________
>> > Alt i ett. Få Yahoo! Mail med adressekartotek,
>> kalender
>> > og
>> > notisblokk. http://no.mail.yahoo.com
>> >
>> >
>> >
>>
>>
>>
>> _________________________________________________________
>> Alt i ett. Få Yahoo! Mail med adressekartotek, kalender
>> og
>> notisblokk. http://no.mail.yahoo.com
>>
>>
>>
>
>
>      _________________________________________________________
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>
>
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