Check my throttle linkage

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mopardude318

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On my ‘74 W200, 360 with a manual transmission. I have an RPM AirGap manifold, a 1” wood spacer, and a Holley 750 Street Demon. AR Engineering throttle cable bracket and return spring bracket for high rise manifold.
My pedal is really stiff, and acts like a light switch. Either on or off, it’s difficult to ease into the throttle. Take a look at the pics, what do you see wrong?

Also, at wide open throttle, the cable stop doesn’t bottom out on the cable, it’s the carburetor that ends the travel...I don’t think that is right?


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When held wide open, cable stop does not bottom out.
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Try reversing the return springs from front top to bottom rear & see if it eases up any.
 
How does the throttle on the carburetor feel if you disconnect the cable and return spring and move it by hand? If its nice and smooth and easy then the cable its self may be buggered.

I have seen where people have installed new carpet or rubber floor mats and they are not trimmed around the pedal well and have the pedal to hang up. My dad did that on his Coronet and it drive the way you describe.

I have had throttle bodies get slammed shut and bind and they too would act off-on but they would ease off ok, it was the on that they we're hung up.
 
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^^All good suggestions, plus one more thing to check: It looks like your cable bracket still may be a bit too low- remember, the throttle linkage travels in an arc, the cable pulls in a straight line. If the cable is low, it takes more force to pull the linkage over that "hump", then pops the rest of the way open; similar to what you're describing.
And don't fret the "cable stop" thing- the main thing is that your throttles open all the way.
 
Throttle cable looks rather long and 1/2 looped. Resistance?

I'm thinking this is it. When you apply pressure to the cable the jacket is going to shift, move, open up, or whatever until it can't then the force will move the throttle. If you were to constrain the jacket it might work better. Removing the loop would be best.
 
I agree with ## 5 and 6. One more thing I'd check is if the cable hold down nut on the AR throttle bracket is so tight it won't let the cable freely move.
 
Throttle cable looks rather long and 1/2 looped. Resistance?
I’m pretty sure that’s an original cable and it was looped like that. Maybe there is a shorter one available and I could eliminate that loop somehow.
 
How does the throttle on the carburetor feel if you disconnect the cable and return spring and move it by hand? If its nice and smooth and easy then the cable its self may be buggered.

I have seen where people have installed new carpet or rubber floor mats and they are not trimmed around the pedal well and have the pedal to hang up. My dad did that on his Coronet and it drive the way you describe.

I have had throttle bodies get slammed shut and bind and they too would act off-on but they would ease off ok, it was the on that they we're hung up.
Once disconnected it feels pretty smooth.
I have no carpet and my pedal assembly is a truck style. See pics


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I’m pretty sure that’s an original cable and it was looped like that. Maybe there is a shorter one available and I could eliminate that loop somehow.

Did your truck have cruise control or Slant in it? Worst case get a Lokar cable. I had to on my Dart.
 
Do whatever it takes to get your carburetor spring and cable elevated to put them into a parallel strait line of pull. Your return spring should be at the top of the return spring bracket, and the bracket itself may need spaced up with a coupling nut or some washers and a longer bolt and stud. This is with an automatic kick down, but it should look similar to this. I think you also need Holley p/n #20-7 throttle lever extension bracket to put the cable attachment point into the correct travel arc. Oh, BTW, that’s a Great looking truck! What’s that color code and what’s it called?

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You have 3 holes on the back edge of the accelerator arm, try running the springs from there towards the firewall in a flat horizontal line.
 
I agree with ## 5 and 6. One more thing I'd check is if the cable hold down nut on the AR throttle bracket is so tight it won't let the cable freely move.

Unhook the cable from the carburetor. Then: First, see if the carburetor moves freely when not hooked up the the throttle cable. Second, see if the throttle cable moves freely when not hooked up to the carburetor.

This should tell you where the binding is occurring.
 
How much return spring load do yo have?
Is this a throttle return spring?
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And two more here?
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Maybe try with just one spring but in the top hole of the bracket.

My 3310 has some downward pull on it and it's just fine. Your cable pin looks somewhat closer to the throttle shaft and more forward than mine. Raising the cable bracket should help I would think.
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That's a linkage spring for the fast idle cam & such.
And you definitely, ALWAYS run double throttle return springs- two forward, one forward and one to the rear, or two to the rear. The factory did, NHRA and other sanctioning bodies require it, and if you've ever had a broken throttle return spring you know why.
 
Okay, here’s another angle. I put the return spring back on top. If I run the springs to the rear, it seems it assists the opening of the throttle, and you lose the function of a return spring.... The cable bracket is definitely lower than the throttle shaft pin. I unhooked everything and moved the cable and throttle through the motions. They move like butter. I’ll upload a short clip.

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Maybe I’m just an idiot...

And it is a V8 cable. This truck is a factory 360, and never had cruise control.
 
FYI, if you run the springs rearward, you attach them in one of the three holes in the linkage below the throttle shaft.
 
Do whatever it takes to get your carburetor spring and cable elevated to put them into a parallel strait line of pull. Your return spring should be at the top of the return spring bracket, and the bracket itself may need spaced up with a coupling nut or some washers and a longer bolt and stud. This is with an automatic kick down, but it should look similar to this. I think you also need Holley p/n #20-7 throttle lever extension bracket to put the cable attachment point into the correct travel arc. Oh, BTW, that’s a Great looking truck! What’s that color code and what’s it called?

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thank you. I don’t think that throttle spacer fits this style carb. Not sure on the color, but I’ll find the code for ya!
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I have that same carb and one of the first things I did was cut the Ford kick down bracket right off it. I’d read some things about it binding at WOT that I didn’t like and we don’t need it anyway. I did try to bind it up at WOT before I cut it off just to see and sure enough there’s not much clearance at all. I can see how it could happen.
There’s a small return spring hole on the bottom of the throttle bracket near the automatic transmission cable hole mounts. It faces down toward the manifold and can be hard to see but it allows rear return spring mounting. I believe it may show it in the manual but I can’t remember and I can’t reference it right now. I might have a pic but will have to check and get back to you. Acts like you may have lots of return spring tension maybe since everything else seems very free.
 
The arc of the pin is rotating upward while you are pulling down with the cable. Raise the bracket.
 
I know it’s not exactly the same set up as it’s an automatic but you get the idea on the return spring.

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