440 vac leak??

[KerryPinkerton <pinkertonk@xxxxxxxxx>]

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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