Can't get the curb idle below 1500 RPMs. Any ideas or suggestions?

You need to see what is keeping the throttle open or causing the high idle.

Check the throttle cable adjustment/transmission kickdown linkage. Is the cable adjusted long enough/linkage not binding and allowing the throttle to close fully? Disconnect them and see if the idle drops. Since you had the carb(s) off, something may not have gone back together properly.

Check to see if the fast idle cam/lever are touching at idle. They should not be touching when engine is warm and choke is fully open (choke plate should be vertical). Next would be the idle solenoid. Disconnect it and see if the idle drops. If the RPM drops, adjust the solenoid. If not, check the base idle screw and see if you can lower the RPM. Check for vacuum leaks.

If none of these things work, check to see if you have manifold vacuum to the vacuum advance at idle (disconnect the hose). If the RPM drops, check the hose connections. You should not have manifold vacuum to the advance unit at idle. If the hoses are connected properly and you still have vacuum to the advance at idle, the throttles are opened too far.

Did you just remove the center carb or all of them?

Take the carb(s) back off and look for anything hanging up the throttle plates (i.e.; throttle plates rubbing on the throttle plate bores in the base, base gaskets hanging into the bores, bent/binding linkage, etc.). If the throttles are open too far, you'll be into the transfer ports in the carbs, not just the idle circuits.

If it idled well before, go back over each thing you touched one at a time...and look carefully for any problems.

You disassembled everything up top. Regardless how it ran before it just makes sense to me that you would have to readjust the linkage when it was reassembled. Did you try to start/run the car without the linkage connected? That might tell you whether it's simply the linkage adjustment or something else like a vacuum leak.

OK, one or more of your carburetors isn't closing all the way FOR SURE. Never, ever, ever start up a six pack car without the outboard linkage(s) connected or you can blow the motor (front/back carbs can go wide open with no way to close them). Here's what I would do:
1. Turn the center carb idle screw all the way out (lowest possible idle). I assume you've already done this.
2. See if you can force (gently) the center carb closed any further by hand. If yes, then your return spring may be weak and/or hanging up somehow.
3. Inspect carbs for anything that may have moved & now interferes with any of the carburetors returning to fully closed (vacuum hoses, plug wires, etc.)
4. WITH ENGINE OFF, disconnect the outboard linkage & see if that lets the center carb close even further. If yes, then re-adjust linkage, re-connect & THEN start engine to test.

5. While the linkage is disconnected (see 4), manually move each carburetor by hand gently to see if any one of them is hanging up. It is very common to have a carb/intake gasket hang up the throttle blades on six packs. (fyi-always best to move carbs open/closed while tightening them down to prevent this....nudging carbs/gaskets so each carb moves freely before fully tightening bolts)


If none of that works.... report back & we'll think of other possibilities

1. done
2. can't
3. will double check
4. did/done
5. never thought of that will have to check

my gut feeling is that issue probably lies with base gaskets. vacuum hoses all hooked up correctly as far as i can tell. got new Holley gaskets for all carbs. unfortunately had to remove all carbs eventhough i tried everything i could to not have to do so. this is the only thing that's really changed as far as materials go. everything was torqued to spec (200 in/lbs) but still just not sure everything is right there. really don't want to have to remove everything again.........

The ones I took off were the black ones. Ones I replaced with were the same style Holley ones with what looked like a metal insert. Never seen the tan ones where do you get those? I thought originals were the thin black ones from Holley with rear stamped on them.