Well, you really need to do the cardboard test with the choke fully open.
It does sound as if your choke is set too rich, but this should not bother
the engine when fully warmed up. Cars of the mid 70's are notorious for
driveabililty problems when warming up, plus lean surge and other ills of
poorly calibrated carburetion, due to the panic in the industry over the new
EPA smog rules, which were very hard to meet with the old technology. I'm
assuming you have gone through the carburetor personally, being careful to
get all the settings "on the money".
If you've said, I missed it: Does the car have the original carburetor, and
what is it? It is sounding like there is a problem with a power valve
(Holley) or metering rod (Carter), which may be easier to fix by replacing
it with one of the new 9636 Carter/Edlebrocks that everyone has such good
luck with - talk to Elijah.
Dick Benjamin
----- Original Message -----
From: KerryPinkerton <pinkertonk@xxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Saturday, March 16, 2002 6:18 AM
Subject: Re: IML: 440 vac leak??
> Ok Dr. Dick, I did that. No noticable change other
> than when I completely choked off the primary with my
> hand (in a leather glove) the engine would slowly lose
> RPM and act like it would die. Note the choke was
> still on as I did not wait for the engine to warm up
> completly.
>
> Couple other things:
>
> When cold, the car misses pretty bad. It fires right
> up but runs rough, shakes and when the throttle is
> pressed will slowly clear and run smoother but does
> not smooth out completly until the choke is opened
> completly.
>
> The plugs are black which indicates a rich mixture or
> misfiring. however after a hard run they are still
> black and mileage sucks more than normal.
>
> The float is set correctly.
>
> I'm thinking about changing the plugs just for grins.
> (oh joy, changing plugs on a 73 is such sweet
> sorrow...) I'm grasping at straws.
>
> Also thinking about pullng the 500cfm Edelbrock off my
> son's mustang and seeing if it makes a difference. i
> have the spreadbore adapter.
>
> Keep those ideas coming.
>
> Kerry
> --- Dick Benjamin <DickB@xxxxxxxxx> wrote:
> > The way to tell if you have a vacuum leak is to
> > remove the air cleaner and
> > then, with the engine idling, slowly put your hand
> > or a piece of cardboard
> > over the airhorn such as to restrict the flow of air
> > into the carburetor.
> > Do this very slowly, progressively increasing the
> > air restriction, while
> > listening to the engine. If at ANY point between no
> > restriction at all and
> > stalling the engine, you hear an increase in RPM, or
> > a smoothing out of a
> > rough idle, you have a vacuum leak for sure. So try
> > that, and let's hear
> > your result before we go any further with the
> > diagnosis.
> >
> > Dick Benjamin
> > ----- Original Message -----
> > From: KerryPinkerton <pinkertonk@xxxxxxxxx>
> > To: IML <mailing-list@xxxxxxxxxxxxxxxx>
> > Sent: Friday, March 15, 2002 3:16 PM
> > Subject: IML: 440 vac leak??
> >
> >
> > > Well, I'm approaching stumped. My 73 runs like
> > crap
> > > and I've messed with it til I'm about out of
> > ideas.
> > >
> > > Here are the symptoms:
> > >
> > > Timing set at 10 degrees BTDC with the Vac adv
> > > disconnected and plugged.
> > >
> > > Vac gauge shows about 17, it used to be about 20.
> > >
> > > I have adjusted on the carb and timing and made
> > little
> > > change in the vac.
> > >
> > > i have disconnected and plugged ALL vac lines with
> > NO
> > > change on the vac guage.
> > >
> > > The car runs right now as well as it's run
> > recently
> > > WITH THE BREATHER OFF. With the breather on it is
> > > very FLAT at high RPM and has a slight bog if you
> > > punch it at idle. Turning the breather lid upside
> > > down and letting more air in helps but not as much
> > as
> > > removing the breather completely.
> > >
> > > Vacumm leak you say. I've tried the starter
> > spray,
> > > propane trick and get no RPM or engine noise
> > change.
> > >
> > > Compression is 130 per cyl.
> > >
> > > Now for the interesting stuff, under some
> > conditions
> > > of timing, I can screw the idle jets all the way
> > in
> > > and the car still runs which makes me think vacuum
> > > leak. Also the car will not idle down below about
> > 600
> > > RPM even with the screw completly backed out.
> > >
> > > Plugs are about a year old but probably don't have
> > a
> > > 1000 miles on the, same with wires, rotor button,
> > and
> > > cap. Cap does not show signs of damage or wear.
> > >
> > > At this point, the only think I can think of is
> > that
> > > there is a vacuum leak around the intake manifold,
> > > probably on the bottom where I can't get to it.
> > >
> > > Before I pull it off, I'd like to hear from the
> > wisdom
> > > of the group.
> > >
> > > Oh, one piece of good news is that my 'ticking'
> > sound
> > > was a bad exhaust manifold which has now been
> > > replaced.
> > >
> > > Kerryp
> > >
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