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Discussion Starter · #1 ·
I have a 3 year old 600cfm edlebrock carb with offroad needles and springs on a well built 401. The problem is one side of the carb is running too rich and making the exhaust temps to high on it's cylinders. I can't adjust it any lower. The floats and vacum check out ok. The engine is just rebuilt and we can't get it running just right. Any suggustions would be great.
anyone have experience with this

78 CJ-7/401/TH400/Quadratrac/35" BFG AT'S

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1,134 Posts
I've been running my 600 for 2 years and have never noticed one side running richer than the other. Did you have your mixture screws on the front adjusted all the way in, back them out until it gets the highest possible idle and then bo back in a 1/4 turn or so? May need to clean your jets out?

/wwwthreads_images/icons/cool.gif Big Ed
'88 YJ, 4" susp,3" body,33's,283 Chevy V8,TH350,4.11's,D30,D35c

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499 Posts
If your using the Edlebrock A.K.A. Webber try the following
I've had this problem also. Turns out that my idle was too high and I was trying to overcompensate with the mixture. start from the beginning. COMPLETELY close the valves, all the way. In fact make sure the idle screw isn't even touching the tang. Then set the mixtures two complete turns out. If you have the manual choke you can set it so it opens the valves slightly. Start the jeep, then as you turn off the choke increase the idle screw until you get the correct idle. Then fiddle with the mixtures. You may also want to double check the float level. I also use the off-road needles and I found the the float level needed to be adjusted more than what the book says. After I figured all that out it ran great.
Good luck


Discussion Starter · #4 ·
Uhhhhh, not to start anything but Edelbrock is the former Carter.

Cut to shape, hammer to fit, paint to match /wwwthreads_images/icons/wink.gif
Project '51 willy's total rebuild /wwwthreads_images/icons/cool.gif

Discussion Starter · #5 ·
I was just looking at my carb upper half while I was installing the offroad needles and seats, and noticed that it didn't look as if both main metering rods were the same length... on further inspection, it turned out that one of the cylinders got some dirt in it, and it jammed the piston in the idle position... This would cause a lean condition, but it might've jammed in the upper position in your case... the manual explains how to check the rods... just a thought..

btw 600cfm edelbrock...

Florida Mud CJ-5
'77 RB304, t-150 D20 4" 35" swampers

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6,784 Posts
*NickC* asked,
*The problem is one side of the carb is running too rich and making the exhaust temps to high on it's cylinders. I can't adjust it any lower. The floats and vacuum check out ok.*

I hope I'm not reading this correctly, or the engine may already be scrap!
You don't adjust the fuel delivery 'lower' when you have a hot set of tubes! Excess heat is a sign that the bank is TOO LEAN already!

1. Look for some small holes at the top of the Venturi throats in the carb. These are mixture air bleeds. Spray carb cleaner down them with the vehicle running. If the idle doesn't change, you have a plugged passage. (get the carb cleaner with the little red tube, it helps a lot for this)
2. Put your fingers over the two outside air bleeds first, then the two inside ones. Holding your fingers over one set should do nothing, the other set should really screw up the idle. If you get no change, you have blocked passages.
3. With the engine off, Turn in the idle mixture screws all the way GENTLY! These screws are very fragile, so DO NOT torque on them.
4. Immediately back both screws out 2 turns.
5. Set the parking brake, and chalk the wheels.
6. Start the engine, and let it get up to operating temperature.
7. Put the vehicle in reverse, so if something goes wrong, it goes away from you.
8. Attach a vacuum gauge to the carbs base plate, or to manifold vacuum,...
9. Turn both screws TOGETHER! 1/4 turn at a time until you get the highest vacuum reading. Both screws must turn together!
10. If you want to see if your idle mixture screws are working, screw them BOTH in the same amount until you get a lean misfire condition, and back them out about 1/4 turn. Then screw in one at a time until you get a misfire. If both cause a misfire, you probably haven't damaged the needles on the end of the screws.
If you can't get it to richen up, or lean out, the screws are messed up, or a passage is blocked.

11. Have a beer, your idle mixture is set correctly.

If you have leaned out the one bank, you may have already burned the valve seats, or a dozen other nasty things. Good luck dude... Aaron.

If Chris Columbus "Discovered" America (with 25 million already here), Can I Go "Discover" Florida?
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