stinking holley probs
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stinking holley probs
I have a 67 F100 with a 390 FE and it has a Holley motorcraft style 2-bbl from Autozone on it (I'm planning on replacing it with a 4bbl and an aftermarket intake later this year). I can't adjust the idle speed! The idle speed adjusting screw doesn't touch the throttle linkage where it should. Essentially I have the thing adjusted all the way down, but it still idles really high. If I grab the throttle linkage and try to push it back some more so it will idle lower, I can move it a little bit, but it seems to kinda stick there. If I then rev the engine a little, it returns to the previous high idle spot I can't get away from. I don't have any vacuum leaks (17" on a tester gauge hooked to intake). I sent an email to Holley asking what to do, and they said to loosen the screws that attach the throttle plates to the shaft and move the throttle back and forth rapidly, then re-tighten those screws, but I don't see how this will even do anything at all...
Greg
67 F100 CS 390 cruise-o
Greg
67 F100 CS 390 cruise-o
Cargo Master
Joined: Jul 2000
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From: Northern California
stinking holley probs
Sounds like the fast idle is kicking in. The way it works is when you pull the choke, a cam forces the linkage to run the carb a bit faster, after warm up, when the choke is released, a spring is supposed to move the cam out of the way so the carb can return to normal idle.
You can check if this is the problem by closing the choke and opening the throttle, it should return back to a point on a little cam that will cause it to idle high. Then open the choke, tap the throttle and the it should return back to normal idle. The spring loaded arm or cam may be stuck.
Look for a small fast idle cam around the linkage area, it might have multiple steps and when engaged, should cause the linkage to open a bit. Some use an adjusting screw, if this is too far out, it would cause the same problem. The fast idle cam should not engage at all when the choke is fully open.
Also, see if the linkage is binding somewhere or the return spring is not tight enough.
You can check if this is the problem by closing the choke and opening the throttle, it should return back to a point on a little cam that will cause it to idle high. Then open the choke, tap the throttle and the it should return back to normal idle. The spring loaded arm or cam may be stuck.
Look for a small fast idle cam around the linkage area, it might have multiple steps and when engaged, should cause the linkage to open a bit. Some use an adjusting screw, if this is too far out, it would cause the same problem. The fast idle cam should not engage at all when the choke is fully open.
Also, see if the linkage is binding somewhere or the return spring is not tight enough.
Post Fiend
Joined: Feb 2000
Posts: 5,130
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From: Brea CA
stinking holley probs
If it’s not on the fast idle cam like Karl says, it could also be binding of the throttle plates within the throttle body bores when closed. When they rebuilt the carburetor, they might have not done a good job centering the plates before tightening down the screws.
What you have to do is remove the carburetor, then just slightly loosen the two screws per plate. With the plates “floating” on the throttle shaft, close the throttle shaft and wiggle each plate until they are fully seated within the bores and you see no light around them. You might have to back out the idle speed screw a little more to do this. Then tighten the two screws per plate while holding the throttle closed
Make sure you don’t loosen these screws too much, just enough to free the plates. They peen the threads on the other side so they don’t accidentally unscrew out and get eaten by the engine.
Barry
What you have to do is remove the carburetor, then just slightly loosen the two screws per plate. With the plates “floating” on the throttle shaft, close the throttle shaft and wiggle each plate until they are fully seated within the bores and you see no light around them. You might have to back out the idle speed screw a little more to do this. Then tighten the two screws per plate while holding the throttle closed
Make sure you don’t loosen these screws too much, just enough to free the plates. They peen the threads on the other side so they don’t accidentally unscrew out and get eaten by the engine.
Barry
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stinking holley probs
It's not the choke. I have a manual choke, and I know it's not open, but I thought I might still have a problem with the cam, like you said, so I checked it out, and it's not even touching. I'm going to try the re-centering thing on the throttle plates one of these days, and let you know how it went.
Greg
Greg
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stinking holley probs
Greg,
One other thing to try is to disconnect the throttle linkage and see if the idle drops down to the stops, that will check to see if the linkage is to short and holding the butterflies open.
Jim
One other thing to try is to disconnect the throttle linkage and see if the idle drops down to the stops, that will check to see if the linkage is to short and holding the butterflies open.
Jim
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stinking holley probs
got that one fixed!
the carb was sucking the gasket between the carb and spacer a little bit, and it was interfering with the closing of the plate, so a new gasket fixed that one up fine. Thanks for the help.
Greg
the carb was sucking the gasket between the carb and spacer a little bit, and it was interfering with the closing of the plate, so a new gasket fixed that one up fine. Thanks for the help.
Greg
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