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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: gildardo01 on February 25, 2014, 08:15:17 am
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hey there hope some one can help me out a bit...
i have a 350 engine with a year old edelbrock that i bought new, its running way too rich and it fouling up the plugs i try to adjust the mixture with the idle screws but it wont respond to any change... i installed a vacuum gagued and it fluctuates at about 15-16hg at idle i think it means the mixture is too rich and/or there is an ignition miss and or minor vacuum leak..or even a sticking valve, i checked for leaks everywhere with carb cleaner and nothing happen... i have a new dissy with new module new cap and even new wires... any ideas what could be the problem? by the way there is a good ground to the engine one ground going directly to the engine and other ground cable going to the starter. another thing when when i accelerate the engine the vacuum drops and then it quickly build back up and reaches about 22hg what does that mean? thanks
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by the way its an HEi distributor. plug gaps are 035
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Did you check the float levels when you installed the carb? Edelbrocks are notorious for being maladjusted from the factory.
What needles and jets are you running? The stock needles and jets are too rich. Engines will run too rich, but on the lean side, they either won't run or can burn up an engine, so the carb mafrs ship them in a stock configuration that is rich enough for most users, because they know most users won't tune the thing.
Did you tune the carb, or just put it on the engine in it's as-shipped configuration?
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Did you check the float levels when you installed the carb? Edelbrocks are notorious for being maladjusted from the factory.
What needles and jets are you running? The stock needles and jets are too rich. Engines will run too rich, but on the lean side, they either won't run or can burn up an engine, so the carb mafrs ship them in a stock configuration that is rich enough for most users, because they know most users won't tune the thing.
Did you tune the carb, or just put it on the engine in it's as-shipped configuration?
i just installed it... and adjusted for idle or at least i thought i did.. i guess there was more to it then... i even have the owners manual for the carb.. but never completly read, just saw a youtube video con installing the carb and did what they did...
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Most likely your floats are incorrectly set, and it is running rich. Then adjusting the idle mixture won't do much.
To check/adjust the floats you just need to take the top off the carb. See the section in the instruction manual. You will need the gasket to put the top of the carb back on. Edelbrock #1499.
See reply #12 in this thread for some other things to do to get it tuned correctly:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=26985.msg225757#msg225757
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today i went ahead and checked the floats and they came in within spec... 7/16 from top plat to float and 1in when they droped... nothing changed.. i still canīt get the idle to adjust with the idle screws.. and there is vacuum where the advance to the distributor is located.. i think thats not supposed to happen until after idle...
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by the way when i took it apart i went ahead and cleaned it up a bit... even though it looked cleaned no dirt no nothing...
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today i went ahead and checked the floats and they came in within spec... 7/16 from top plat to float and 1in when they droped... nothing changed.. i still canīt get the idle to adjust with the idle screws.. and there is vacuum where the advance to the distributor is located.. i think thats not supposed to happen until after idle...
Which port on the front of the distributor is the vacuum advance connected to, the driver's side port or the passenger's side port?
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today i went ahead and checked the floats and they came in within spec... 7/16 from top plat to float and 1in when they droped... nothing changed.. i still canīt get the idle to adjust with the idle screws.. and there is vacuum where the advance to the distributor is located.. i think thats not supposed to happen until after idle...
Which port on the front of the distributor is the vacuum advance connected to, the driver's side port or the passenger's side port?
the driver side...
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today i went ahead and checked the floats and they came in within spec... 7/16 from top plat to float and 1in when they droped... nothing changed.. i still canīt get the idle to adjust with the idle screws.. and there is vacuum where the advance to the distributor is located.. i think thats not supposed to happen until after idle...
Which port on the front of the distributor is the vacuum advance connected to, the driver's side port or the passenger's side port?
the driver side...
OK, that's correct. And you will get vacuum at idle. The other port kills the vacuum to the distributor at idle, and will give you balking coming off idle. That was emissions nonsense. Read this on that:
http://www.corvetteactioncenter.com/forums/c3-technical-performance/60830-ported-vs-manifold-source-vacuum-advance.html
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The idle screws control fuel bleeds for idle. All the way in is no fuel. What happens if you screw both idle mixture screws all the way in? Not tight -- but until they hit bottom.
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The idle screws control fuel bleeds for idle. All the way in is no fuel. What happens if you screw both idle mixture screws all the way in? Not tight -- but until they hit bottom.
thats the thing nothing happens.. it just stays running it idles yes but nothing happens.. does not stumble or anything, its running of the cruise circuit i guess its called..
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I would try: 1) turn the idle mixture screws all the way in; 2) back off the idle speed screw until the engine quits; 3) back the idle mixture screws out 2-1/2 turns; 4) start engine and adjust from there.