1yesfan

My 74 88 with the 350 rocket motor has the electric kick down at the gas pedal, no cable from carb. There has only been a few times that it has kicked down when I have got on it. I have noticed that the carb hits a flat spot/bogs down a hair right at that moment where it would kick down for the passing gear thus not catching the passing gear.
Is this a carb issue or maybe the kickdown stuff is messed up.

Fun71

I vote for kickdown stuff. Even if the carb is way out of adjustment the transmission should not care - it gets the signal to downshift based on throttle position regardless of the carb's actual operation.

1yesfan

most of us have owned old cars that at certain points the carbs bog down a little. Usually when cold if choke is not working right, maybe off the line from a stop, etc. Mine does NONE of that, it can be bone cold out and i hit the gas pedal twice and it fires right up and never hesistates, just right at the kick down spot it seams. Seems to me that if the switch at the pedal was bad, the trans is getting no signal and when I hit the gas the carb would not bog out a little and would just slowly accelerate a little more????

1yesfan

I have done the procedure at the switch on the gas pedal. Push in the switch, then push the gas pedal all the way down and let them out.

1yesfan

if there is no cable to the carb, what is opening up the two back barrels when you get on it?

Fun71

There has to be a cable (or rod linkage on earlier cars) to the carburetor; otherwise there is no way to control the throttle opening.

The "back two barrels" are opened by the secondary throttle linkage. When the front throttle plate is opened to a certain point the secondary linkage starts opening the rear throttle plates. Once the throttle plates open, air can begin flowing through the rear bores and the secondary air valves can start opening.

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joe_padavano

Just so we're all on the same page here:

There is a throttle cable from the accelerator pedal to the carb lever. There is only one cable. As shown above, there is an internal link on the carb that opens the secondary throttle plates once the accelerator pedal moves to a certain point. The linkage is progressive such that the primary plates open first, the secondaries start later, and all four are fully open at wide open throttle.

The two plates on top of the carb are NOT the secondary throttle plates. Those are the secondary air valves and only open in response to airflow through the carb. You will NOT see them open if you are simply revving the throttle in PARK. They only open under load. There is a spring that controls when and how fast they open, and if the spring has lost tension or the dashpot leaks such that the air valves open too soon, the carb will bog. Troubleshoot this and fix what needs to be fixed.

You can easily test the kickdown switch. With the car in the air and the engine off but the key in the RUN position, listen under the car at the trans pan while someone floors the accelerator. You will hear the kickdown solenoid click. If not, troubleshoot this problem. Start by testing for power at the wire that plugs into the trans. If there is power with the accelerator floored, the problem is inside the trans. If no power, trace the circuit back. Your Chassis Service Manual tells you how to do this.

1yesfan

There is just one cable to the carb.

Fun71

Yes, that is the way it's supposed to be.

svnt442

The kickdown switch is a known failure point. Remember that the switch is more than 40 years old at this point and that is the most likely thing to fail.
I would unplug it and use a VOM to check continuity to make sure it is or is not working. Then make sure you have power at the plug and if you do then you can manually jump the plug and if the trans still doesn't click, then you know the problem is inside the transmission.