Missing throttle stop - 521

[Thaiyoon]

Again, thank you guys for helping me out.  When I got my 521 project, the throttle on the carb was wired as pictured.  I've continued trying to use it the way it is but it's pretty mickey mouse and I'm at the mercy of the spring returning my carb to idle.  Sometimes it does and sometimes I have to rev it a couple of times to get the rpms to drop down to idle (sticky throttle).  Anyway, what parts am I missing?  I've tried to find a picture of some kind of plate that must be missing that the compressed throttle adjustment screw would push against.  Can you help me out?  Thanks in advance.

[thisismatt]

While there could be a stop there, you really should have a stop on the pedal itself. The pedal should not be limited by the carb/cable.

[Thaiyoon]

Thanks Matt but I don't believe the pedal is being limited.  If I'm seeing this right, the pedal pulls the throttle open and the pictured spring (as well as the pedal spring) is returning the throttle when the pedal is not being pushed.  My problem is the spring sometimes does and sometimes doesn't  bring the throttle back to idle position.  There is an adjustment screw pictured which pushes against nothing.  I'm thinking there must be a mounting plate, that has a spring attached to it, that the adjustment screw would push against.  Even if the throttle cable had slack in it, the system would still work.  Maybe I'm dreaming. 

[datzenmike]

 

The screw pictured is probably for adjusting a dash pot, something not used on a 521* and probably from a car and usually used on an automatic. 

 

The spring is pulling off center to the pull direction. This is also not good for throttle shaft wear and partly to blame for the hang ups. The spring should be in the same line as the exposed cable. Make a bracket that will bolt to the intake manifold mounting bolt. The spring does not need to be excessively stiff, just enough to pull the pedal back up when released.

 

*This is not a '70 carburetor. Where does that small vacuum line go?

[Stoffregen Motorsports]

Many things can make the throttle hang up. I would start by checking to see if the pedal is hanging on anything, like carpet or wires. Next, I'd fab a simple bracket for the return spring. Use a manifold bolt to hold it in place.

 

If the throttle shaft is badly worn, that can also make the throttle hang up. Also, a choke linkage that's out of adjustment can do the same.

[Thaiyoon]

Thanks guys, I'll be creating a new system more in line with the cable.  Here are some more photos of the surrounding area to hopefully answer your question Mike about where that vacuum line is terminating. Excuse the dusty motor, it just came back from the painter.