Okay, it'* probably not that.

Did it arrive pre-adjusted for this engine or does it need to be adjusted?

im pretty sure its just a basic carb with factory settings.

Accelerator pump?

edelbrocks hate high pressure, your stock or current fuel pump may vary well put out more than6psi which has a tendency to push past the seats and cause a rich idle and off idle mixture which would be stumble. A company named power last also sells a piece to install on the nozzle that makes the spray pattern more conical and helps the edelbrock off idle a lot especially with stumble. There’* a certain level to be expected esp when you don’t adjust your choke and screws which operate your idle mixture and some people need to adjust the.. floats.... I FORGET the part. Jets. Maybe. Anyway, install a regulator for pressure, a power blast spray enhancer, and adjust your timing then adjust your carb. Remember timing is super important nothing will be right if it’* off.

check your distributor lately? It’* up front fortunately in a v8 Buick, pop off the cap and rotor and look at the centrifugal weights. They kick out when it spins fast, I’ve had weights on a sbc stay kicked out snd that caused it to hang at high rpm but actual ran better because timing was r tarded

Its working, when pressing slowly accelerator the car stumbles, when pressed fast, car goes normally.

Distributor has been set, i dont remember the number because i was not the one working on it, and its pretty fresh too, some hei distributor. It works correctlty. At least i think so.
But i will forward your message, maybe some miracle happens and this pos works at last..

sounds like it’* maybe not the proper vacuum advance setting. Or the mechanical advance is too heavy or has weak springs, as in, maybe needs a recurve. Some aftermarket distributors have a lot different advance curve than a stock. As in, total timing adjustment is less usually so that would require adjustments usually in instructions.

i say check vacuum hoses and advance for proper adjustment. If it’* Stumbling it’* probably too advanced to get any off the line power, when you slam it your dropping vacuum to nothing and your shooting a nice shot of fuel into that, which you know what that means?
more fuel, less advance because there is no manifold vacuum applying on the vac advance and that pump shot of fuel is followed by secondaries yanking air and metered fuel in, the pump working faster as it climbs to keep up with the demand.

id still look at fuel pressure, because it can still be the scenario of too much fuel and perhaps the opening of the plates allows it to lean enough to give good acceleration, it’* all potential factors, looking at is a good idea. My plow truck has the edelbrock but it doesn’t actually need the regulator, the pump has internal leakage amd I just out a check valve in so I don’t get drain back, and it doesn’t produce enough pressure to overpower my edelbrock. If I change the fuel pump I’m gonna need to regulate or get an edelbrock pump internally regulated at the proper psi

what kind of fuel filter is there

Fuel filter is after fuel pump, basic clear plastic paper filter. I think its in the wrong place, id put it before fuel pump. Fuel pump btw is stock.
I told them to check the vacuum advance and distributor etc.

Filter is in right place. After pump before fuel rail..

as I though. You have the filter edelbrock gives you with a new carb. Replace it. It’* trash. It can fail in weird ways, it distorts, it’* garbage. I used premium only and the medium degraded in months.


wix makes a nice metal 3/8 in and out filter that has a screeen etc , very nice

I’m glad I asked, I chased issues from my clear plastic filter.

A lot of good advice here, so I hope the OP has followed some of that during the past two years from the original post!