how to adjust a carburator

[dead civic]

1979 Corvette 350 5.7l with a cam
Edelbrock Intake manifold RPM
*Carter 4bbl carb

I've been looking on line how to adjust it and it does not work for me... can some one please help me.

looked up online:

If it doesn't start, then set the screws at a base setting of two turns "out". A dual plane intake separates totally the intake runners between cylinder 1,3,5,7 and 2,4,6,8. Therefore 1/2 of the intake manifold serves fuel to the right bank and and the other half to the left bank. Therefore, the adjustment screws need not and should not be turned "in sync". If using a vacuum gauge as the writer above suggests, turn each screw independently for the highest vacuum. Then back-off screw 1/4 turn.

If using a tachometer, the suggested way. Then turn one screw clock-wise for highest RPM (rich condition) and then turn the screw counter-clockwise (lean condition) until engine just stumbles; turn screw clockwise 1/4 turn. Do the same for the other adjustment screw.

^^^Ive tried this to avail

this what truck is doing now. once its in motion all is good. but when i stop it bogs and sometimes shuts down till it gets going it works again. what am i doing wrong?

and helpful input is greatly appreciated. thanks.

[Corts60]

First of all, WELCOME!

We're gonna need a little more info from you. Is the carb rebuilt? Does the engine die anytime you put it in gear or just at stop lights after driving? What is your timing set at? Is it back firing through the exhaust or popping through the carb at all? Do you have a tach and if so, what RPM are you idling at in gear and in park?

This will help us determine better what is going on.

[dead civic]

thanks for the welcome.

sorry for my messed up post and my messed up answers coming up.

*the card I'm sure is just as it came from factory.
*the engine idles low and smooth, sorry I don't have a tach.
*It does not die when i put in in gear. It only dies for the initial take off from a dead stop
*not sure of timing.
*It was backfiring ofter. but i changed plugs today and I'll get an occasional backfire every now and then.

[Corts60]

Originally Posted by dead civic

thanks for the welcome.

sorry for my messed up post and my messed up answers coming up.

*the card I'm sure is just as it came from factory.
*the engine idles low and smooth, sorry I don't have a tach.
*It does not die when i put in in gear. It only dies for the initial take off from a dead stop
*not sure of timing.
*It was backfiring ofter. but i changed plugs today and I'll get an occasional backfire every now and then.

OK. Two tools you're gonna need: timing light and a vacuum gauge. These will be handy for the rest of your car hobby life.

Because you said you are popping through the exhaust, it makes me think you are running rich. Double check that your timing is set. Not sure on your smallblock but it could be around 4-8 degrees BTDC. That'll get you close anyhow.

After timing is checked/set:

I always set my idle/mixture screws (two screws on the bottom of carb) using a vacuum gauge. You want to get the highest possible reading you can. A stock cam could produce anywhere from about 17-21 in. hg., but if you have a bigger cam, you might produce less. With the engine off, seat both screws (softly) to the bottom and then back them out 1 1/2 to 2 turns. Start it up and with the vacuum gauge connected to a manifold vacuum port, start adjust one screw at a time until you've achieved the highest reading you can. Then stop.

That will get everything set the way it should be and we can go from there.

[dead civic]

I have a timing gun. I'm gonna to look up how to check my timing. i need a vacuum gauge tho.

when adjusting the screw witch one do i start with? also am i supposed to only adjust clockwise or can i also com out with screw?

left or right? what is each for?

[wilkin250r]

A vacuum gauge is one of your best tools for diagnosing idle problems. If it idles all well and fine, even when you put it in gear, it doesn't sound like a vacuum leak, but I wouldn't rule it out completely.

The screws on the front control the idle fuel mixture, and they both essentially do the same thing. The left controls the idle mixture in the left venturi, and the same for the right. And yes, it's perfectly acceptable to adjust both clockwise and counter-clockwise.

Basically, the first the we want to make sure is that your idle mixture and timing are set correctly. If that doesn't fix the problem, we'll take the next step, but we need to make sure these things are correct first before we move on.

When you're finding the initial setting of "2-turns out", the first thing is to turn the screw all the way in, obviously, but it doesn't need to be tight. You want to just barely tighten it to the point it stops turning, you could almost do it with your fingers. Then exactly 2-turns out, even a quarter turn will make a difference in your final setting.

If the timing and idle mixture don't fix your problems, we'll likely move on to the vacuum advance or the accelerator pump.

[motornut]

sounds like you may wana check the dist vac advance is ok

[Bowed]

Originally Posted by dead civic

*the engine idles low and smooth

*It does not die when i put in in gear. It only dies for the initial take off from a dead stop

I'll get an occasional backfire every now and then.

Maybe the pick up coil inside the dist . the pickup coil wires can break because of flexing and throw off the vacuum advance .