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Holley Linkage Binding?

5K views 22 replies 9 participants last post by  Hotrodder000 
#1 ·
Thoughts? If I let the throttle snap, it will close all the way. Close softly, and it sticks till I push it. Also cant seem to get the low end massive hesitation to go away but she rips big time when the secondaries come in. Installed heavy springs to point that I could barely push pedal. No change.

 
#4 ·
It’s your choke/fast idle coming on. Look at the choke flap when you push on the throttle lightly. You can see the fast idle cam is going onto the first step because the choke flap moves closed slightly.

Loosen the fast idle screw on the passenger side of the carb.

With the engine warmed up and running, check what the fast idle speed is set to.

With the engine off, open the throttle. On the right hand side of the carb is a red plastic lever, by the choke. From under the choke pot, push up on that plastic. That will set your fast idle. You can also open the throttle, push the choke flap closed, then close the throttle.
Then start the engine.
If the fast idle is higher than 1200, loosen the fast idle screw.

You will have to put your original throttle return springs back on.
 
#5 ·
pockets is right on that, it's the choke assy. either not open all the way and the coil may not be hot enough to relax it, so the carb can go to base idle. That's why I like a manual choke.
 
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#8 ·
Thanks for the info. I will have to play with it tomorrow. I let it warm up for awhile and took it for a spin, still hanging out unless i snap the throttle. Noticed the fast idle set screw bottoms out on the carb spacer when throttle is open. I guess I am going to carve out some of the spacer to allow full travel.
 
#9 ·
I have had issues with the secondary throttle blade not closing, and I wound the spring for more tension to close it. You could try that too.
 
#10 ·
You can see the choke blade close when it's revved at the 7 second mark and see it fall back open when pressure is applied to the throttle lever at the end.

When the blade closed slightly it engaged the last step on the fast idle cam, and when it opened the throttle dropped back down to the curb idle speed screw setting.

Readjust the choke setting.
 
#12 ·
To me it looks like the black cap that contains the choke spring needs to be reset so it opens fully when warm. That would cause the choke plate to close and make the car idle off the fast idle cam. The black cap has 3 screws that hold it in position. Loosen those screws and turn the cap so the choke plate just opens all the way while your holding the linkage off the regular idle screw. There is a notch in the cap that lines up with markings on the housing to give you an idea how far you go. You probably only have to go a notch or two.
 
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#16 ·
It's on the other side of the carburetor. Watch this video around 2:07 you will see the fast idle screw. Personally I wouldn't touch that screw and would rotate the black plastic cap clockwise one notch at a time till the choke plate opens all the way when it is hot. https://youtu.be/0H5IBSFgYJE
 
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#17 ·
So that did the trick with the throttle not closing all of the way. Now it idles just fine when in park at 900 rpms and wants to stall when in gear. Also runs like complete crap all the way through acceleration. I have an appointment on thursday to get it dynoed and tuned but trying to get it a little closer for the guy so it doesnt cost me extra...lol
 
#18 ·
Richen the mixture screws. If you have them set lean, the engine runs leaner when under load in gear, and is usually the cause of the stalling. As for running like crap through acceleration, there is a multitude of things that can be.

Do you mean it hesitates when you hit the throttle?

Start with ensuring you have no more than 7psi fuel pressure at idle, and the floats are set mid way on the sight glass. Then adjust the accel pump adjustment bolt properly. You should not be able to pull up on the bolt with the spring on it, and see a gap between the head of it and the accel pump lever.
 
#19 ·
Yeah I played with the idle mixture screws and they didnt make much of a difference. It hesitates through the entire band. The dash fuel gauge is reading 6.5 psi but the gauge that I have on the rail is reading 4 psi. I would assume the gauge on the rail is more accurate? I guess I should try bumping it up and see what happens. I did also follow holleys youtube videos on adjusting the accelerator pump.
 
#20 ·
What are the specs on the engine? You will want to get the timing setup first.
 
#21 ·
What happens when you turn the base idle screw all the way off so it idles as slow as possible ? try that and then see if the mixture screws start to respond to the changes you try.
If that works then you can then advance your base timing a little to get your idle speed back up some.
The idle circuit feeds fuel to the engine all the way through the off idle speeds so it is important that the mixture screws respond to changes.
 
#23 ·
It is a ZZ4 crate motor. Does not have vacuum advance...yet. It has a MSD setup with a blaster 2 coil and standard distributor. I did purchase the stock GM distributor with vacuum advance and was planning on installing that and removing the MSD. It hasnt run right since I purchased the car so I am just trying to get it back to stock to make things right. Im told these motors can be finicky if messed with too much.
 
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