Bit of a stumbling problem, ideas?
 

So I'm a little perplexed. Basically, until my engine is just about up to temp, the car has a stumbling problem when going from idle to moving. Basically, when I give it gas (anything more that simply laying my foot on the pedal) the motor cuts out, and stumbles. Once I get the car rolling it runs just fine.

Heres the important facts. Rats nest removed, running dizzy vacuum of furthest forward nipple. New plugs, new dist cap and rotor, new plug wires, timing set correctly (to the best of my knowledge), and the accelerator pump has been replaced since I thought that might have been the issue.

Any ideas? I'm just blaming it on the fact is carbureted.

sounds like your accelerator pump needs adjustment - the pump shot isn't starting early enough. back the adjustment nut out a turn or two, then check to see if fuel comes out of the AP nozzles as soon as you open the throttle. if not, back it out some more. this is done with the engine off and looking down into the barrels.

Not sure if you are familiar with the AP nozzles so here's a pic just in case. Centre of pic there are two nozzles pointed downwards, look for a thin stream of fuel coming out
http://img42.imageshack.us/img42/4773/install8.jpg

I found something else out that might be a big clue. If the car is idling, and I go and push the accelerator pump lever in, the engine stumbles.

Probably because you're forcing fuel down the throats...?

When you say back the adjustment nut do you mean the idle mixture screw or which one? Also, if it was not adjusted correctly, wouldnt the engine always stumble and not just when its cold?

He's talking about the accelerator pump lever adjustment.

so backing that nut out a couple turns will advance the shot? or lean it out some

when you replaced the accelerator pump, did you rebuiild the carb?

No I did not rebuild the carb. The stumble problem existed before I did the accelerator pump as well, which was the reason i replaced it, but it doesn't seem to have fixed anything. However I did just replace the fuel filter and pump as well.

i would suggest rebuilding the carb. replace both needles and seats, blow out all of the air bleeds, check and adjust the float level if necessary, and ensure you clean the float bowles out completely and make sure you remove and clean all four jets.

I've got the kit to do so. I'm just a little worried about messing something up. Thats why I didn't bother to begin with. What would be cause the stumble if it wasnt something to do with the acc pump?

I took a video to make it a little easier to tell whats going on. The first rev and the last one it happens on. The tap you hear is my foot hitting the pedal. I'm giving it roughly 1/4 throttle I'd say, normal amount to be leaving a stop light.

http://img535.imageshack.us/img535/8907/1000290.mp4

I checked the AP and it seems to be working fine. I also tried monkeying with the adjustment screw, turning it up to 4 turns in and 4 turns out from where it was with no noticeable difference. Problem is, I can't get the motor to do this when it is warmed up so I have a very small window to work with

Mine does the same thing. I have not figured out what it is yet. I am thinking i might just deal with it till I buy a webber =)

seeing as how my car is an automatic, its a bit of an issue knowing that my car could conk out at any light until its good and warm

Testing with the engine off and looking at the pump nozzles as I described above will tell you if this problem is related to the AP

backing the nut out will advance the ap shot, it may not be shooting fuel early enough resulting in stumble

I did look at the pump when the car was off, it appeared to be shooting a nice stream of fuel

Ah ok. The important thing is that fuels comes out literally as soon as you touch the throttle, eg tap the throttle down lightly and it should come out

if that's all good I can't think of anything else.. Not so familiar with the automatics

Double checked my pump today with help from a friend. Looks spot on. Now I'm thinking maybe its just dirty jets? The carb had been sitting for about a year while i was playing with the rebuild last year

my holley did the same thing . it would stumble until it was just about completely warmed up . my issue was with the choke . i didn't have it connected . sounds like you are having choke issues too.

Shouldnt be. My choke is still hooked up and working, I use it to warm the car up (keeping the idle high) and it kicks off automatically when its warm like always