What closes the primarys on a 65 TBird with a 4100 remanufactured Autolite carb

[sseebart]

Originally Posted by makrie

Regardless of whether the rod raises or lowers the pedal what happens to your primaries if you lose positive tension on the shaft connected to the carburetor? Does your engine idle properly? Is there something else besides this rod closing the primaries on your stock setup?

Thanks in advance!

I can double-check later today, but if memory serves, the primary butterflies can just flop around if the rod tension is removed.

I have an Edelbrock, which doesn't accept the original Ford linkage at the carb. The clip Ford used originally is strong and secure--it can't really come apart. This is how mine looked a while ago, using a set screw to hold the rod to the pivot:



If the set screw on mine were to come loose, the throttle would be all over the place, so I added that helper spring to ensure the butterflies would close in the event of a failure. I use a somewhat different setup these days, but still not as robust as the original Ford solution.

~Steve

[HeadacheGuy]

The secondary lock out I referred to is on the right side of the carb. The diaphram linkage has a "kicker" so the secondaries can't stick open as the throttle closes but if the lever is bent it can bind the primaries. If this were your case however the throttle would feel sticky below about 1/4 throttle but still may be worth looking at. I'll post pic if you don't find the problem in your other linkage.

[Popsashburn]

Here are the connection points on both ends

[makrie]

@Popsachbum... Thank you so much. It's apparent I'm missing some kind of return spring. Do you believe the setup pictured is accurate for your year? I only ask because the two 4100 carbs I have are slightly different from each other in regards to the primary pivot. I assume neither were original to the 65 TBird. One appears to have a tang with a hole for a spring but also has a completely useless bracket pivoting on the same shaft. The spare (w/an earlier accelerator pump) is closest to yours as pictured.

[Popsashburn]

The locations on both carbs for your return spring

[Popsashburn]

The other carb with location of spring marked