Hey guys- Just replaced the pesky Holley on my 71 Dart with a nice Carter. Even completed the fuel line mod! So far, so good. The carb just needs a bit of fine tuning. Any tips? It seems to idle a bit rough after starting, warms up OK, then idles low/rough after driving for awhile. I'm a novice and not sure where to start. Thanks!

Sounds as if your idle speed and mixture need adjusting.

The mixture screw is the one at the very base of the carburetor, pointing forward-rightward. Carefully turn it closed (clockwise) until it seats. Do not force it, just seat it gently. Then back it open 1½ turns, paying careful attention to the clocking of the screw slot to judge how far you've turned it. This 1½-turn-out position is in the (very) general ballpark, but it's not a spec, it's just where you set it so that the engine will run, no matter how poorly, so you can warm it up to do the final adjustment.

Start the engine, set the idle speed to spec (the rearmost of the two screws on the throttle lever, with their heads on the driver's side of the car), then close the mixture needle clockwise ¼-turn at a time, slowly, until the engine just begins to drop RPM because it's too lean (use your ears to detect this). Then, you open the needles back counterclockwise ¼-turn at a time or so, working slowly and keeping track of the number of ¼-turns, until the engine just barely begins to drop RPM because it's too rich. Then, you close the needles clockwise half the number of quarter-turns you counted between lean fall-off and rich fall-off, and that's your final adjustment. Then re-check the idle speed (use a tachometer), adjust as necessary, and you're all done.

Rough idle can also be caused by vacuum leaks, spark plugs and any number of other things.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Do you have any play in the throttle shaft? This is common problem on old carbs. Spray some starting fluid onto the throttle shaft with the engine running and listen closely. If the idle speeds up or smooths out, you have a vacuum leak around the the throttle shaft.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Hopefully, by this time next week I will have a Carter on my rig and this wore out Holley gone! The shafts on it are both shot - that's where my vacuum leak is coming from.

Wish I could have gotten the Carter first instead of messing with this damn Holley.

The guy building it for me says he will have it "race" ready? I'm guessing he will have it at least in good shape! Should bring the rig to life. With the Holley on here and leaking, it runs okay, but I am not driving it because of the lean condition - don't want a toasted piston!

Can't wait to get it on and try it out!
Later,
Dan

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"I may be slow, but at least I'm not very fast!"
'69 A108 - 225, 727, 3.55, MSD6AL, a.k.a.-the brick

A race-ready Carter BBS...?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Compared to the Holley that's on there now!
LOL
Meaning the rig will be ready to roll.
The race ready was me - thinking that with a fully working carb I should at least be able to turn a tire once in awhile!

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"I may be slow, but at least I'm not very fast!"
'69 A108 - 225, 727, 3.55, MSD6AL, a.k.a.-the brick