85 GT Carb question

[RazorbackGT]

Hey guys, got the car back today after carb rebuild, original 4180 c, come to find out secondaries were not kicking in at all, car is running a lot better, but I noticed after pulling it out of gear, idle is not returning, it's staying up around 1500 or so, I kick accelerator and it comes on back down, any ideas?

[Walking-Tall]

There's a few instances around here where people have had to UP the throttle return spring force, either by increasing pressure from behind the factory cable spring, or adding another pull spring to the equation might help. Pop the cable off the carburetor throttle bracket to see whether the intake anchor bracket didn't get somehow bent backward, not allowing easy return to idle, being held open a bit by the cable. Around 1500rpm doesn't sound like idle solenoid dysfunction, but might be sticky choke linkage, letting the fast-idle stuff effect return to idle...

[qikgts]

What he said ^^^^!

[RazorbackGT]

OK, I will check that out, much appreciated!

[homer302]

Yeah, sounds like it's all pretty clean after the rebuild and sticking just a bit. I would put some miles on it and get things used to moving again before stressing too much. The extra spring can't hurt of course.

[mrriggs]

Check that the secondaries are closing fully. Mine weren't because there wasn't enough preload in the daiphragm spring. Tried swapping to a longer secondary diaphragm spring and that didn't help. Tried bending the link rod so the secondaries would be forced shut when the primaries close but that only caused the primaries to bind and hang open. I suspect that the rod on the secondary diaphragm is too short even though it's supposed to be the right one. I got tired of fighting with it and just tied the secondaries shut. The hanging idle went away but, of course, that isn't a permanent fix. Still need to figure out why the daiphragm can't close the secondaries.

[Walking-Tall]

Check that the secondaries are closing fully. Mine weren't because there wasn't enough preload in the daiphragm spring. Tried swapping to a longer secondary diaphragm spring and that didn't help. Tried bending the link rod so the secondaries would be forced shut when the primaries close but that only caused the primaries to bind and hang open. I suspect that the rod on the secondary diaphragm is too short even though it's supposed to be the right one. I got tired of fighting with it and just tied the secondaries shut. The hanging idle went away but, of course, that isn't a permanent fix. Still need to figure out why the daiphragm can't close the secondaries.

I wonder... you think maybe a possible mismatch of diaphragm and housing with that? The lip around the round steel base on the bottom of the diaphragm stopping against the bottom of inside the diaphragm housing? That lip could be eliminated or some clearancing inside the housing bottom... ? Stem extension at some point would only end up not allowing full opening with upward diaphragm travel or the spring stacking solid. Just had a better idea: sit the stem into a deep socket that fits inside the round steel part, and tap the center of the diaphragm steel where the stem attaches downward some... maybe it got jacked upward somehow in the center at some point...