Bill,
I don't know what carburetor you have, but I assume it is a Holley. The
Holley power valve is vacuum operated and changing power valves only
results in altering the level of vacuum that opens it, the actual
metering is done by restrictions in the metering block. What timing
settings have you tried? You could do away with the power valve and run
main jets only, but of course this would make it rich in the mid range
when you got it right on the top. Another thought, make sure that you
have adequate fuel supply, there may be something the is restricting
fuel flow which would make it lean out under high demand.
All of this 'great' advice comes from someone who hasn't run carburetors
on a race motor since I had six Stromberg "97" on a 300 cu in Desoto
back in the very early sixties. I do know though that problems like this
often have a simple fix. Back to the Basics!
I am still a believer in throwing out what others do and finding what
works for me. Combinations are the key. Some run leaner with less timing
and others may try more fuel and more timing. Although I have not often
had the opportunity to do it, the dyno is a great place to experiment.
Tom, Redding CA - #216 D/CC
Bill Bennett wrote:
>
> ----- Original Message -----
> From: "Bill Bennett" <benettw@earthlink.net>
> To: "Thomas E. Bryant" <saltracer@awwwsome.com>
> Sent: Sunday, May 14, 2000 10:55 PM
> Subject: Re: Carb sizing/ ignition timing
>
> > Strange as he would say this. I have seen so many jet changes done
> on
> > this motor going bigger each time till it slowed down. The motor
> seems
> > to always want more gas. I wonder does the power valve have anything
> > to do with it. I know they made a couple of different types some
> > flowed more than others. On the street motors I have built I had
> > always just measured the vacuum at idle and sized the power valves 2
> > inches less. I never worried about the flow rate. Don't know about
> > race motors.
> > BillB
> >
> > ----- Original Message -----
> > From: "Thomas E. Bryant" <saltracer@awwwsome.com>
> > To: "Keith Turk" <kturk@ala.net>
> > Cc: <land-speed@autox.team.net>
> > Sent: Sunday, May 14, 2000 10:20 PM
> > Subject: Re: Carb sizing/ ignition timing
> >
> >
> > > Keith,
> > > Sounds to me like it is lean in then power range. At light to mid
> > range
> > > cruise the main circuit supplies the fuel, when you lean on it the
> > power
> > > circuit has to provide extra fuel.
> > >
> > > Tom, Redding CA - #216 D/CC
> > > Keith Turk wrote:
> > > >
> > > > Saw something interesting the other day on the dyno thought I
> > would ask
> > > > about it...
> > > >
> > > > with the Engine at 3000 rpm the egt was around 1200.... as I
> > rolled into the
> > > > throttle and the Rpm started Rising so to did the EGT ...
> actually
> > getting
> > > > to an unacceptable range based on my EGT gage and the motors I
> > have run with
> > > > this set up.... I want to see about 1375 and it was well over
> > 1500..
> > > >
> > > > So my Question is if the Carb was to big how would that manifest
> > itself...
> > > > and if the ignition timing was to far advanced what would I
> > see.... any
> > > > thoughts?
> > > >
> > > > Keith ( Nahh I ain't totally clueless... Just Bored ) ( Hey
> Mom..
> > Happy
> > > > Mothers day)
> > >
> >
> >
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