Adjusting carb but cannot get idle

I'm adjusting the carb on my 1600 beetle. Thying to solve my stalling
problem.

All other tune-up stuff is ok.
Set idle cam to book
Set small screw to 2.5 turns out.
with engine running set the rpm's to 850 using the big screw
after 20 seconds or so it drops to about 550 & i cannot get it above
that.

What Next?

evanevans wrote:

> I'm adjusting the carb on my 1600 beetle. Thying to solve my stalling
> problem.
>
> All other tune-up stuff is ok.
> Set idle cam to book
> Set small screw to 2.5 turns out.
> with engine running set the rpm's to 850 using the big screw
> after 20 seconds or so it drops to about 550 & i cannot get it above
> that.


1) Did you drive the car a couple miles to warm up first?

2) Year of car? Is it bone stock, orig vac advance?

3) 30PICT or 34PICT?

4) Is the throttle plate fully closing at idle?


Often, idle problems are caused by dirt particles in the
tiny idle fuel passages. After it drops to 500 RPM,
try very slowly opening the throttle by hand. Is there
a smooth transition to higher RPMS, or is there a "dead"
zone or even a drop-off in RPM? That could give a clue.

Normally, I wouldn't implicate it, but is the manifold
heat working?

When the RPM drops off, is it possible a couple cyls
aren't firing? Pull each plug lead off and see if there
is an equal effect.

This kind of problem isn't easy to trace; you need all
the input you can get in symptoms.

Speedy Jim
http://www.nls.net/mp/volks/

Thanks Jim. The manifold heater is working. That was were i first
started trying to solve my problem. The car is a stock 74. My next step
is to remove the carb & rebuild it. I believe that a circuit must be
clogged.

With the choke active until warm-up it idles well & maintains a stedy
rpm. Once the choke is fully open It idles in slow osculating pattern
of rpm's over say a minute or two until it slows to a stall. The
adjusting screws of the carb (big screw) seems not to effect the rpm's

Temp fix - if you need on a daily driver.

Ajust the choke so it doesn't completely open.

You will get about 1 minute driving between cold and warm where it doesn't
want to idle, then it will run fast, off throttle, but it will be drivable
till you sort it properly.

Rich

"evanevans" > wrote in message
ups.com...
> Thanks Jim. The manifold heater is working. That was were i first
> started trying to solve my problem. The car is a stock 74. My next step
> is to remove the carb & rebuild it. I believe that a circuit must be
> clogged.
>
> With the choke active until warm-up it idles well & maintains a stedy
> rpm. Once the choke is fully open It idles in slow osculating pattern
> of rpm's over say a minute or two until it slows to a stall. The
> adjusting screws of the carb (big screw) seems not to effect the rpm's
>

evanevans wrote:

> Thanks Jim. The manifold heater is working. That was were i first
> started trying to solve my problem. The car is a stock 74. My next step
> is to remove the carb & rebuild it. I believe that a circuit must be
> clogged.
>
> With the choke active until warm-up it idles well & maintains a stedy
> rpm. Once the choke is fully open It idles in slow osculating pattern
> of rpm's over say a minute or two until it slows to a stall. The
> adjusting screws of the carb (big screw) seems not to effect the rpm's
>

LOL The "osculating" pattern does suggest clogging.
You need hi-pressure compressed air and total disassembly.
A good soak in solvent helps too. Don't be too
disappointed if it doesn't solve the problem on the first (or second)
try...

Jim

Unscrew the idle jet located over the alternator on the side of the carb.
Use a tiny tiny wire to clean out that debris clogging the jet. Sometimes
compressed air does not clean it out.
When you rebuild the carb you will still be cleaning out this jet among
others.

You also need to make sure that the electromagnetic cut-off valve is
working. This in the one close to the throttle arm and has the wire going
to it. Turn on the ign, don't start the engine, and unplug and replug the
wire. You should hear a click each time. Sometimes these valves loosen
some so you need to make sure that it is tight to the body of the carb.

later,
dave
(One out of many daves)

"Speedy Jim" > wrote in message
. com...
> evanevans wrote:
>
> > Thanks Jim. The manifold heater is working. That was were i first
> > started trying to solve my problem. The car is a stock 74. My next step
> > is to remove the carb & rebuild it. I believe that a circuit must be
> > clogged.
> >
> > With the choke active until warm-up it idles well & maintains a stedy
> > rpm. Once the choke is fully open It idles in slow osculating pattern
> > of rpm's over say a minute or two until it slows to a stall. The
> > adjusting screws of the carb (big screw) seems not to effect the rpm's
> >
>
> LOL The "osculating" pattern does suggest clogging.
> You need hi-pressure compressed air and total disassembly.
> A good soak in solvent helps too. Don't be too
> disappointed if it doesn't solve the problem on the first (or second)
> try...
>
> Jim
>

Thanks guys ! After all the heat riser cleaning & carb rebuilding my
problem turned out to be a vaccum leak. The hose that goes from the
intake manifold to the air cleaner was causing all my problems. I
plugged it up at the manifold & i'm off & running. Why it was never a
problem until recently is what i do not understand!