2 barrel air fuel mixture?

[corymcrae]

what would be the right adjustments on the air/fuel mixture screws for my 1962 283 v8? as your looking at the carb which screw is fuel and which one is air as in right or left?

[javadoc]

Which carb do you have?

[corymcrae]

rochester 2bbl

[C-10 simplex]

Not the best picture, but where the yellow arrow is pointing to and in the same place on the other side of the carb. So, basically at the base of the carb and in front. 2 screws.



i think there's only 3 screws on a 2G; The two at the base which control BOTH air and fuel mix for each barell---the one on the left for the left barel and the one on the right for the right barell, so you've got to adjust both to get everything equalized.

The other screw on/at/near the throttle arm controls both curb/normal and hi-step idles.

NOTE: i'm not a carb expert, i'm just someone who has had to learn about carbs and fuel systems due to nessesity.

[corymcrae]

what would be the correct number of turns if i were to screw them in all the way and then back them out equally?

[C-10 simplex]

Well, that would depend from engine to engine, truck to truck etc. There's no set number nessesarily for a particular setup.

i don't really have time to get into it whole-hog, and maybe someone else can chime in (translation=i'm not exactly sure about it) concerning the setting of these screws.

i guess you're supposed to hook up a vacuum gauge and turn one of the needles at a time for highest vacuum reading, then do the other.

If no vacuum gauge, then turn one screw in until you get the engine running a little rough, then just back it out just until the engine smooths out. Repeat with the other screw. P.S. stay the hell away from the fan at all times!

All these adjustments should be done after engine warmed up and at curb idle.

If you want to try the screw em both in all the way and then back them out equally, then maybe 2.5 turns out after they go in all the way may put you in the ballpark, but i don't think you should do it that way.

Someone else should probably really chime in here.

[corymcrae]

ok ill hook up a vacuum gauge and see what it tells me thanks guys.

[protrash64]

2.5 to 3 turns is what I've seen, generally speaking, in regards to the Rochester carbs. It should put you in the ballpark.

[Winola73]

Originally Posted by C-10 simplex

i guess you're supposed to hook up a vacuum gauge and turn one of the needles at a time for highest vacuum reading, then do the other.

If no vacuum gauge, then turn one screw in until you get the engine running a little rough, then just back it out just until the engine smooths out. Repeat with the other screw. P.S. stay the hell away from the fan at all times!

After doing the second screw you'll probably need to go back to the first one and tweak it a little. I usually go back and forth a couple times between the mixture screws. As mentioned do it with the engine warmed up and the idle speed about 600 RPM.

If you don't have a vacuum gauge, get one. If you have no other diagnostic or tuning equipment you should have a vacuum gauge. I mount one permanently on the dash in all my older vehicles.

[C-10 simplex]

Ok, now i need help.

What's basically happening now is that i can't get a consistent idle speed; Sometimes it will idle at 700-800rpm in gear. And then, sometimes it will idle at 400-500rpm. And when it idles at 400 or below, it will stall out.

There's no binding in the cable that i can detect. Also, the return springs seem ok, i think?

One of my theories is that maybe sometimes the idle screw sometimes gets stuck between the 3rd and 4th(last) positions? Even though i think the choke is working properly.



Also, this obviously is not the carb on the truck, but it is identical.

Any other suggestions?

[geezer#99]

Choke setting is a little rich. Loosen 3 screws on choke and gently turn with a large flat screwdriver.

[C-10 simplex]

i like that train of thought, but could you explain a little further---because when fully warmed up, the choke plate is open all the way (fully vertical).

[geezer#99]

Time to start a new thread. We shouldn't highjack this one.

[C-10 simplex]

That's true; i'll start a new one in the engine section.

[geezer#99]

Include some pics of both sides.