More 289 Engine Questions
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From: Virginia
More 289 Engine Questions
my 66 mustang 289 v8 with edelbrock carb is having some problems. the throttle response is really bad with hesitation before it kicks in and then runs okay with just a small miss. it has an edelbrock carb with a spacer. is this spacer neccesary? i assume the flat spot is carberation problem? the electric choke is not hooked up so the choke is wired open. also i noticed the wire on top of the distributor was not tightt and is corroded bad. should there be something stickig inside the hole in the distributor cap that i hooks too? on the coil there is. now it is just a circular hole with brass around the outside. another problem is some oily residue coming out the back pipes. im getting new plug wires soon. i hope all this mess is just ignition and carberation. another thing the idle is good and smooth thanks for any help
Postmaster
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From: iowa
what carb are you running? A 600cfm? The spacer isn't hurting anything. The flatspot or hesitation is a timing issue. A rich mixture will cause poor performance on edelbrock worse than on a holley. You want your a/f screws set the highest vaccum. I have found that about 1.5 turns out on the edelbrock is the best.
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The Edelbrock is an excellent carb if it is tuned right. If you have the book on the carb, read it closely. If not, go to Edelbrocks web sight and they have it online. You have an idle circuit, cruise circuit, front barrel power circuit, and rear barrel power circuit to tune. Plus you can tune the acc. pump. The wrong springs on the metering rods will cause that carb to stumble all over itsself. I tune the Edelbrocks with O2 sensor. The carb is tricky, yet simple. have not put one on yet that was anywhere close to right out of the box. On most engines, the 600 seems to be rich at cruise and lean at power. I prefer to have it slightly lean at cruise and hig stoich at power. But for starters, you need to be slightly lean at idle with engine up to temp. After having said all that, the major part of your problem is probably timeing. Is dist vacuum advance? If so, is it working? The 289 shouldn't need the spacer.
Last edited by ga302p; May 6, 2004 at 11:19 PM.
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"....it kicks in then runs okay...." This sounds like the acellerater pump circut isn't working right to me. As mentioned above, the metering rod springs need to be correct to prevent stumbles, but unless this has been tampered with, I doubt they will be too far out. The idle circut, or the idle screws only effect idle A/F mixture, and should not be in opreration at all other RPM's. On AFB type carbs the exell pump piston should be replaced fairly ofton. If this piston leaks you won't get a good pump shot causing a bad stumble. You can also control the volume of the pump shot by placing the pivot arm holes into different slots. However, the pump piston needs to be at the float level or below. If the pump piston is above the float bowl level then it will pump air with the gas or it will not give a pump shot to the squirters at the correct time. The float bowl levels on these carbs are critical and it's not really consistant. It's also difficult to monitor and set.
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In addition to any carb problems, the vacuum advance on the distributor may be bad. If so, you're not getting that extra advance when you jump on the gas and the car hesitates.
It sounds like you need new wires and cap as well.
Also, the stumble may be caused by a bad accelerator pump on the carb.
When you tromp on the gas, the engine needs 2 things - an extra shot of gas to richen up the mixture, and an extra shot of timing advance to compensate for the richened mixture. Thus, the accelerator pump, and the vacuum advance. If either one is not working, it will cause the effect you describe.
The oily residue in the pipes doesn't sound good. Does the engine smoke? Probable bad valve guides and stem seals.
It sounds like you need new wires and cap as well.
Also, the stumble may be caused by a bad accelerator pump on the carb.
When you tromp on the gas, the engine needs 2 things - an extra shot of gas to richen up the mixture, and an extra shot of timing advance to compensate for the richened mixture. Thus, the accelerator pump, and the vacuum advance. If either one is not working, it will cause the effect you describe.
The oily residue in the pipes doesn't sound good. Does the engine smoke? Probable bad valve guides and stem seals.
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From: Virginia
i replaced plugs, wires, rewired coil, changed oil and filter and now everything is much better. car is running good, just a little skip between idle and gas and the residue in the pipe now only occurs when first started. it really had me worried but for now i think i just need the carb adjusted and it will be okay. thanks for all the help
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