Stumble Off Idle

[bordin34]

My 73 400 has a really bad stumble right off of idle. The car feels like it wants to die like it is cold I need to give it more gas to make it get past it. The car has been tuned up and has a 670cfm holley on it.

[4aThrill]

I would say try your timing and tuning in your carb in alittle more, I have the same 670 Holley on my 383 I changed the power valve and the Accelerator Pump Cam still trying to find the right pump cam to have in there.   

[4aThrill]

what is your vaccum in park and then in drive then once you know that you can change your power valve easy switch.

[bordin34]

I don't know my vacuum and I had a mechanic tune up the car a couple weeks ago. The powervalve could be bad because it used to backfire through the carb, but I thought it had blowout protection. The mechanic has a 1970 Challenger and he set the timing, mixture, and float levels.

[4aThrill]

power valves go out, first i would check the vaccum make sure you don't have any vaccum leaks. then if no leaks then switch out power vlv see if it makes a difference easy and fast change. 

[Rob R]

Give it some more (jet) then some shooters if the jet shows improvement then up the shooters 31 to start...that's a pretty small carb for a big block and I expect it's very lean.