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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