New Edelbrock Problem
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Logistics Pro
Joined: Oct 2002
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From: Valley Center, CA
New Edelbrock Problem
Last week I finished the overhaul of my fuel system on my 54 f100. A new fuel tank, filters and fuel pressure guage to feed my monster 289. 
Then I installed my pertronix unit in the Mallory distributer. Everything idles smooth now. Unfortunately, my Edelbrock carb seems to be running rich at idle now. I tried adjusting the idle down to I'm guessing 6-700 rpm. Then I turned the idle mix screws counterclockwise. They had no effect!
I turned them both until they gently bottomed out . No effect. With all the comotion in the fuel system, does it sound like I might have gotten a load of gunk in there so that the gas is bypassing the idle passage? Does that even make sense? I have a 1406 with minimal hours on it. Fuel pressure 4.5psi. Any ideas on why this is occurring? Solutions? Thanks, John
Then I installed my pertronix unit in the Mallory distributer. Everything idles smooth now. Unfortunately, my Edelbrock carb seems to be running rich at idle now. I tried adjusting the idle down to I'm guessing 6-700 rpm. Then I turned the idle mix screws counterclockwise. They had no effect! I turned them both until they gently bottomed out . No effect. With all the comotion in the fuel system, does it sound like I might have gotten a load of gunk in there so that the gas is bypassing the idle passage? Does that even make sense? I have a 1406 with minimal hours on it. Fuel pressure 4.5psi. Any ideas on why this is occurring? Solutions? Thanks, John
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Logistics Pro
Joined: Oct 2002
Posts: 4,489
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From: Valley Center, CA
Thanks fenders, I do not have a schematic of the Ede carb. Are you refering to the idle screws as needle valves? Or is there a seperate needle vvalve and seat? Thanks again, John
Post Fiend
Joined: Feb 2001
Posts: 6,328
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From: Iowa
John
I am talking about the needle and seat assembly. Part of the float assembly. But your float is probably fine. I'm not talking about the idle mixture screws. The lid has to come off your carb. You'll need a minor gasket kit along with the needle and seats if you choose to upgrade them.
I am talking about the needle and seat assembly. Part of the float assembly. But your float is probably fine. I'm not talking about the idle mixture screws. The lid has to come off your carb. You'll need a minor gasket kit along with the needle and seats if you choose to upgrade them.
Post Fiend
Joined: Feb 2001
Posts: 6,328
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From: Iowa
John
What Cobraguy said is correct. But you said you are running rich which is not a sign of a vacuum leak. Why do you think you are rich?
What Cobraguy said is correct. But you said you are running rich which is not a sign of a vacuum leak. Why do you think you are rich?
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5th Wheeling
Joined: Oct 2003
Posts: 40
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From: California
This is my first post, but I had to jump in somewhere. If you screwed the idle mixture screws in until they stopped and the engine is still idling, it must be getting fuel from somewhere. The first thing I would do is shine a flashlight down the carb while the engine is idling. If you see fuel coming out of the main discharge nozzles and the engine is idling, it could be something like a float too high. This is probably not due to gunk in the carb because if the needle was off it's seat it would be spewing fuel out of the bowl vent big time. Here's another quick check: pull the pcv valve out of the valve cover while it's idling and the screws are still all the way in, leave the valve on the hose. If the engine dies when you do this then it was getting fuel from a fuel contaminated crankcase.
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From: San Diego CA
Let me try to explain whats going on. You have a vacuum leak. The engine is so lean you have to crank up the idle until the butterflies are slightly open to get it to stay running. you have now taken the idle circuit out of the picture. You are idling the truck on the main circuit thats why it's running rich. Any adjustments now won't effect any change. Find and fix the vacuum leak your idle will be very high. The idle mixture screws are actually air bleeds kind of a controlled vacuum leak. If you screw them all the way in you take away the air and the engine will die and if you pull it out the engine goes too lean and will die.
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Logistics Pro
Joined: Oct 2002
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From: Valley Center, CA
Thanks guys, I'll check it out this weekend after I finish the column install. On your question fenders, I think that it is running rich because I can actually see a slight amount of smoke in the exhaust and the smell is "rich" also. It would be great to get it running right because this weekend is supposed to be dry! Soon the rains will be here in Sac and the cruising will be done. Thanks again, John 
Post Fiend
Joined: Feb 2001
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From: Iowa
John
I can share my carb schematics when I return to Iowa. Rich is certain you have a vacuum leak. You very well may and I would check thoroughly for one. It's very tough to work drivability issues without being there. Make sure your ignition is working perfect before you touch the carb. Check your timing and make sure the spark plugs are not fouled. (real important) If they are clean I would be inclined to agree with Rich. If they are black you likely have a fuel control problem. My Edelbrock 1406 didn't last a thousand miles before it started blowing the needles off the seats occasionally. It's a weakness with this carb. Whenever it did it I got a lopey idle, some black smoke out the tails and of course a gassy smell under the hood.
You can get a tuning kit from Edelbrock which will allow you to dial in the carb perfectly to your 289. They usually work pretty well right out of the box though. Wouldn't take long to get your 30 bucks back though if you can improve your MPG by a coulpe per gallon.
I can share my carb schematics when I return to Iowa. Rich is certain you have a vacuum leak. You very well may and I would check thoroughly for one. It's very tough to work drivability issues without being there. Make sure your ignition is working perfect before you touch the carb. Check your timing and make sure the spark plugs are not fouled. (real important) If they are clean I would be inclined to agree with Rich. If they are black you likely have a fuel control problem. My Edelbrock 1406 didn't last a thousand miles before it started blowing the needles off the seats occasionally. It's a weakness with this carb. Whenever it did it I got a lopey idle, some black smoke out the tails and of course a gassy smell under the hood.
You can get a tuning kit from Edelbrock which will allow you to dial in the carb perfectly to your 289. They usually work pretty well right out of the box though. Wouldn't take long to get your 30 bucks back though if you can improve your MPG by a coulpe per gallon.