79 Silverado all kinds of issues

[blazer74]

The dial thing is the choke adjustment. Rich/lean is simply the length of time the choke stays on by increasing or decreasing spring tension.
Rich tighter,  lean looser.

The mixture adjustments are probably covered with caps of some sort that limit or prevent adjustment. They can usually be removed.

You said by removing the vac advance
hose an plugging the idle is more controllable but still stalls. Doesn't make sense to me.

Where did the carb come from? Pics?

When you go from park to in gear how does this affect idle speed?  How much does the rpm change?  Mechanical advance coming in too soon can cause idle trouble.

Where did the dist come from?

If you want to eliminate the brake booster just plug the line to the booster and see what happens but you will not have power brakes.

If timing and ignition are good stalling when you come to a stop sounds like a large vac leak or not enough idle fuel.


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[RE4PER]

Both came from auto zone I will try to figure out how to send pics

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[blazer74]

Me personally would cap off all vac lines on the carb that  go to anything other the the carb itself and see if the idle improves.




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[mcintyrederek]

One vacuum line that gets overlooked is the transmission vacuum modulator.  That line normally goes directly into the intake manifold and is located between the carb and distributor.  The line is large enough in diameter that if it's broken or split somewhere, it can definitely cause rough off-idle conditions and certainly lose it altogether when it's in gear and you're stopped.

To be certain the line or modulator isn't leaking, just pull it off the manifold and cap it until you're sure.

Mack.

[rich weyand]

You keep saying 8 degrees AFTER.  You don't mean that, do you?

Is your vacuum advance on ported vacuum or manifold vacuum?  It should be on manifold vacuum; ported vacuum will make it idle like crap, especially if the timing is off.

[RE4PER]

My vac advance on the old carb went into the carb. The new carb is set up different is the only reason I an not sure if lines are right. Didn't come with a diagram. But it's a stock replacement but a different choke.

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[Irish_Alley]

from my experience the vacuum port on the base of the carb is manifold and the one thats a little above that is ported. dont know if its true for all carbs but i know it is on the edelbrock

[mcintyrederek]

I have actually seen a time where plugging my vacuum advance into the true manifold vacuum made it idle like crap.  I found out that the idle mixture was way incorrect.  Emissions controlled engines ran a lean mixture, late ignition timing and no advance on the distributor at idle.. hence, "ported" vacuum which is only present at off-idle conditions, ie, when the throttle plate is opened.

If it's a "stock replacement" (Quadrajet) then I have experienced rough and super poor idle because of a lean mixture.  I just went though this on my 350 engine and finally fought it long enough that I bought a new carb, which is working flawlessly now.

What kind of carb is it?  If it's a Quadrajet, it will say so on the driver's side with a stamp in the aluminum. 

If you're trying to figure out which is ported vacuum or straight manifold vacuum, if you can get it to run at idle speed, just stick your finger over the vacuum port.  If it's sucking vacuum at idle, it's manifold vacuum.  If no suction, it's ported.  ALL your vacuum lines should go to straight manifold vacuum, unless you're running emissions control and you're running ported spark, with a lean mixture and late ignition timing (by late, some of these engines ran at zero base timing, I have even seen some at 2 degrees after TDC !!)  Otherwise, everything goes to manifold vacuum, even the advance on the distributor, with the base timing set at a good starting point of 10 degrees BEFORE TDC and a good idle mixture to keep it running smoothly when you plug the dizzy advance canister in.

Take some pics of the carb.

Mack.

[RE4PER]

I took pictures but can't upload for some reason. The carb was purchased at autozone. Part number 3-3622. You can see it on there website. It's a heated choke. So just to be clear. Timing wise since it seems to be coming back to timing, I unplugged vacuum advance from the distributor. Plugged the line turned cap till the balancer was at 8 degrees. Plugged vacuum advance back into the distributor. Upon doing this she ran fast as heck in Idol. With the Idol screw pulled out a decent amount. But still had the same issue of applying breaks (which requires me off the gas) shutting off. How I get around is I pulled vacuum advance off and plugged it. As well as when stopping shift in netrual and feather gas if needed. Shift back in drive when I'm ready to go again.

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[roundhouse]

I'd pick up a vacuum gauge and set the timing with the gauge
There are some good YouTube vids for setting with a vac gauge

Basically you just move the distributor slowly while it's idleing  and watch the gauge and leave it where it makes the highest vacuum

And look for some large vacuum leaks 
Could be brake booster leaking or somewhere



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[RE4PER]

OK I'll try that..  Where do I get the gauge

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[roundhouse]

OK I'll try that..  Where do I get the gauge

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Any auto parts store should have one


I never pay any attention to the timing light
I just advance it a tiny bit and run it up the nearest hill at full throttle
Then advance it a little and do it again
Until it rattles    The retard it just a bit

The vac gauge will set it fine.   And will also show up other problems


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[RE4PER]

OK now I'm confused just put out a fire on my truck. #6 plug wire was on fire while I was driving. What would cause that?

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