What's up with this, I have 69Z, 302, a 4776 600 dbl pumper and after I pulled off the bowls and metering plates, changed the jets, pwr valve, new gaskets, put it back on and it idles at 1500 with the butterflies closed. No adjustment seems to affect it, what did I do wrong?

You're pulling air from somewhere... I'd check the bowl and metering plate gaskets to be sure they are the right ones and installed the right way... Also look for any vacuum leaks at the base of the carb and verify both pri and sec throttle blades are adjusted properly. If the sec's are open you could be running off them... Does the idle mixture screws effect teh idle at all?

If everything is adjusted right I'd suspect you dropped without knowing a tiny piece of trash down the carb and now its caught on a valve. I actually did this once and it ended up just blowing out the exhaust after running awhile.

You're pulling air from somewhere... I'd check the bowl and metering plate gaskets to be sure they are the right ones and installed the right way... Also look for any vacuum leaks at the base of the carb and verify both pri and sec throttle blades are adjusted properly. If the sec's are open you could be running off them... Does the idle mixture screws effect teh idle at all?

I just got my DZ started and broken in. The exhaust is not connected to the headers so I could not work very long on it until later this week when it is connected. However, after 20 minutes I tried to get it to idle down, but it would not. I suspect a vacuum leak (I changed primary jets to 72's as this seems to be a normal modification for a 4053) and will check for any leaks. The idle screws do not affect the idle. It won't idle below about 1200 rpm. I can back the main idle screw off and the car will die. This carb was purchased newly rebuilt. I have a lot to learn about carb tuning.

Silly me, I didn't have the pcv hose connected on the back of the carb as I was just hooking it up for a test run before I re-connected everything. It idles good now that the hose is hooked up. Thanks for the responses.