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Six Pack Idle help!!

1968rt

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Had an older set of carbs on my motor. Idled good, just ran a tad rich. I decided to rebuild another set. I had them boiled out and plated and then did a fresh rebuild. The new carbs will not idle at a reasonable rpm. When I bring it down around 900 rpm I get a surge for a minute and then it dies. Carbs have new gaskets including the base gaskets. Im ruling out a vacumn leak for now. Could it be the float levels?

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First of all, I won't claim to be an carb expert, so I'm sure others will chime in.

(original text deleted - see R413's note below)

Bottom line is to simply the equation. Work on one thing at a time.

Good luck!
 
Last edited:
Im guessing the center carb is the problem
 
NEVER disconnect the outboard linkage and drive
Or run the car. That linkage will save your life as it’s the only thing that closes the outboard carbs.

Make sure they are closing all the way and not sticking Before closing completely. Then with the center carb at idle speed and off the choke cam adjust the linkage so the outboards close all the way.

if you want to run on center only then remove the vacuum lines only.

Outboard carb operation:
vacuum lines open them
Mechanical Linkage closes them

@hsorman sorry for the red X but this is a big issue. I wish You would delete that part of your post.
 
NEVER disconnect the outboard linkage and drive
Or run the car. That linkage will save your life as it’s the only thing that closes the outboard carbs.

Make sure they are closing all the way and not sticking Before closing completely. Then with the center carb at idle speed and off the choke cam adjust the linkage so the outboards close all the way.

if you want to run on center only then remove the vacuum lines only.

Outboard carb operation:
vacuum lines open them
Mechanical Linkage closes them

@hsorman sorry for the red X but this is a big issue. I wish You would delete that part of your post.
R413: No worries. You explained why and that makes sense. The main point I was trying to make is that if the linkage is not adjusted correctly, the OP could have idle problems due to the outboard carbs being partially open due to linkage issues.

From a safety perspective, I will edit my post.

Hawk
 
Nice thing you had it running good with other carbs so we know the rest of engine and ignition is probably OK.

It really does sound like a vacuum leak. Make sure outboards are Fully closed. How much idle vacuum does it have? Do you know cam specs? Did you change timing?

Problem float level for dying? Not really if it has some fuel in the bowls. Don’t need very much gas to idle. But all 3 need fuel, idle circuit in all 3 of them.
 
I have 12lbs vacumn, fluctuating to 14. running the Mopar .528 -284. I never checked the power brake connection.
 
6 Pak's were generally not good runners from the factory. That's why I could get many at reasonable prices in the mid '70's. Make sure you don't have any vacuum leaks and float levels are close. Then tuning involves usually the end carb idle mixture screw adjustment, hidden behind plugs in the base plate, which must be removed to get to the screws. Usually a slight richening makes a big difference, combined with the idle throttle blade screws which are under the baseplate. It takes some tinkering with these two things, in combination with the center carb idle mixture screw and idle position screw. The stock jetting on both center and end carbs is real close and so is the center carb shooter size. My experience on all the '69 1/2, '70 & '71 carbs with the Edelbrock manifold.
 
Had the problem before, 440-6 Challenger, freshly gone thru carbs. Could never get it to idle worth a damn no matter what I did. The problem was the throttle shafts / bores were worn out. Reworked the throttle plates with bushings and problem solved. Tri power setups were always a PIA back when they were new... worse when they're old and worn. Check and make sure your throttle shafts don't wobble around in the plate. It's a vacuum leak from hell brother, trust me.
 
Had the problem before, 440-6 Challenger, freshly gone thru carbs. Could never get it to idle worth a damn no matter what I did. The problem was the throttle shafts / bores were worn out. Reworked the throttle plates with bushings and problem solved. Tri power setups were always a PIA back when they were new... worse when they're old and worn. Check and make sure your throttle shafts don't wobble around in the plate. It's a vacuum leak from hell brother, trust me.
Good point, that throttle shaft leak tricks most of us.
 
I did the shaft bushings on the older set. On the newer set the shafts were still pretty tight.
 
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