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Old 12-09-2007, 02:04 AM
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Carb issues, advice needed

I have a holley 600, manual choke, vac secondaries. Reman from Jegs.
My problem is that it is running way rich at idle, black smoke, fouling plugs.
Replaced power valve, checked and rechecked float levels, fuel pressure is right. Still having same problems.

Replaced metering block gaskets, cleaned and reassembled carb, still same problems.

Should my next step be to try a new metering block? Or get a new carb?

At my wits end here, its the only thing left keeping me from driving my car for thew first time since I got it. (4 years)

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Old 12-09-2007, 02:31 AM
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PV don`t control the idle, the idle circuits do, you set the idle via the screws on the side of the primary metering block, clockwise leans, counter clockwise richens, set the idle with a vacuum gauge to it`s highest setting.
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Old 12-09-2007, 06:45 AM
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also the metering blocks might have been modded from previous owner if its a remanufactured card.
another thing to look at is the gaskets have to be installed correctly.
if the gasket is in backwards itll block off a critical air bleed causing over rich condition
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Old 12-09-2007, 08:13 AM
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PV doesn't control the idle, however if they blow out (used to be extremely common) it will make the exhaust so rich your eyes will water. That would have been the first logical step. The reman part is the clincher ,I think, What exactly is done on a reman?? I flogged a Ford tri-power on and off for over a year, it had similar symptoms, seemed to go away everytime I replaced the metering block gaskets...for a short time. When I drove it and the throttle dropped closed it would begin again. I found,after much other chasing that the thin lip that the metering block attaches to had become warped over the years with constant bowl removals and replacements. This is aggravated if someone does a lot of jetting changes. I disassembled all 3 to the bare body and machined the front of the carbs( all had the edges "pulled" up) flat again. They worked great after that. The metering block gasket wasn't getting a good seal and when the high vacuum of the throttle dropping closed occured it would pull air by it and create a leak into the vacuum side of the power valve causing it to always be open and creating a very rich condition.
One other thing you might want to check is that the air bleeds in the airhorn are clear, so air pressure and carb cleaner should clear those. Also make sure that your bowl vents aren't being obstructed by the air filter. Some low filters can interfere with a vent tube signal.
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Old 12-09-2007, 08:17 AM
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[QUOTE=DoubleVision]the idle via the screws on the side of the primary metering block, clockwise leans, counter clockwise richens, QUOTE]

Except the emissions ones made in the early 70s...they are just the opposite. That was supposed to keep you from richening them up too much... I guess it could have one of those metering plates by some quirk.
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Old 12-09-2007, 02:49 PM
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internal leak

Do this test. Turn in one of your idle screws all the way. The engine should stumble and die. Then do the other screw. If it doesn't stumble, you have an internal leak and the cause of your rich idle.

Most likely it is a bad float chamber gasket. However, there are other potentials on a rebuilt carb.

The other immediate possibility is that the carb was jetted too rich. If the idle circuit is ok you might want to check what jets are installed on the primary side. Also, make sure your secondaries are not actuating at idle.

If your idle circuit is normal, you can also check your accellerator pump nozzle. It should show no drip at idle and should shoot out a nice stream when you blip the throttle.

If you think it is the jets, go down at least 2 sizes to try first.

You can also call the Holley custom shop for advice. They are really good to deal with. 1-888-465-5395

Good luck on it

Arn
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Old 12-11-2007, 01:42 PM
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Watch out with rebuild carbs. Sometime the pri. metering could have come different Holley carb. It could be calibrated for motors with large cam. It require low manifold vacuum for idle circuit to function. If yours has fairly high vacuum it will pull too much fuel in idle circuit causing a rich condition. Changing jets will not affect the idle or air fuel mixture. It affects when it is running about 1500-2000 RPM on up. I was you, I replace the primary metering block.
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