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1967 CHEVY PICKUP 350 V8; HOLLY DOULBE PUMPER MOD 4776 600 CFM NEW CARB 1000 MILES AGO. At IDLE the engine is LOPING; Will stall at idle unless rpm are increased. CHANGED OUT VACUUM LINES;Engine ran good for sever hundred miles; It appears that a large amount of gas is flowing from the REAR PORTS IN CARB. when at IDLE;
How can I adjust this fuel flow ? Black soot at tail pipe.
If engine rpm is increased black soot droplets are blown out. Engine rpm gauge fluctuates when truck is driven.
:( :confused:
 

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'Stock' is just wrong!
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Gas Puddling?

You don't say if it's stalling at idle because you're running an automatic trans, or if it's stalling-out in neutral/manual...

Heavy gas in the back ports seems odd, unless the rear butterfly isn't opened-up yet, which allows you to "see" the gas (instead of the front ports that are opened-up into the intake.

Black soot tells you what you already know, too-rich. I'm guessing your plugs are just as black. Causes are:
• poor ignition (dist/coil/wires/plugs)
• too much fuel pressure (bad/no regulator, should be around 6.5-7#)
• stuck floats in the bowls
• carb isn't level
• idle-screws not adjusted right

I'm guessing it's not a jet-problem per-se, since you're not complaining of operation at part-full throttle. I'm betting on too much pressure from your fuel-pump, I've never had a problem with a new Holley or Carter out of the box. I guess you could've knocked something loose in a rusty gas-line that's stuck in your floats?

Good luck!

-Kustomizer
 
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