I have a 1968 chrysler newport sedan. 383 2bbl. She has always hesitated while accelerating, but now at around 40 mph she starts bucking and miss firing and will stall if I do not reduce speed. I'm new to working on carbureted engines and honestly I have no idea where to start. She is pretty much all original. I don't get to drive her much.Now that she can't do over 40 I can't even take her to work! any suggestions are appreciated.

 

Welcome.

First find out what carb you have sounds like it needs a rebuild and could be a Holley 2210, don't hold me to that.

If you search google images yours might pop up, and if you know the model search you tube there are lots of step by step rebuilding videos. If you have never rebuilt one don't be shy it's not that difficult. I have heard many have bought so called rebuilt carbs from so called reputable companies and just bolted another problem on their engine, do your own if the throttle shaft is not too worn.

 

The problem is, "normal" troubles are compounded by "how old" these are

This could be engine problems such as valves, fuel, or ignition / related electrical

In other words it could be darn near anything

1....I'd start with a compression / leakdown test. Google leakdown testers, you can make 'em or buy e'm

2....After you have determined the engine is sound, IE valves not sticking / leaking / etc, Get into the service manual and read the section on camshaft and determine if the chain seems to be OK. Basically you turn the crank back / forth while watching the dist. rotor to judge chain slack. If there is any doubt, estimate cam timing by looking in the engine specs. Determine valve opening events for intake, and judge that on the dampener.

3...Take a jaundiced look at ignition components. Are the points (still used?) set right, in good shape? Timing OK? Roter, cap in good condition? How 'bout wires and plugs?

4...NOW perform a backyard balance test. Get a grounded probe like a clip lead / screwdriver or even a 12V test lamp. Pull the dist wire boots loose and loosen the wires. Get yourself an insulated pair of fuse pullers. With the engine idling as smooth as possible, and warm, pull the wires out of the cap one at a time. Slide your grounding probe into the dist cap. This prevents spark crossfire.

Note on a test tach and / / or vaccum gauge the drop in RPM, and LISTEN to the engine. Each cylinder should drop and sound the same

5....Now attack fuel. Look in the manual. There are procedures to test the fuel pump. You need a pressure / vacuum gauge. Fuel systems are simple, but dirty. You have to get your hands dirty.

Get a gasket for the sender. Pull the sender and inspect, clean the filter sock, and inspect for damage / rust / goo.

Replace both hoses......the one from the sender to the fuel tubing, and the one up front from the fuel line to the pump. While you have this off, test the pump for vacuum. Read the manual

Replace the filter. "Rig" your test gauge up there with tee fittings to monitor fuel line pressure. Take a short test drive and see what the pressure does.

 

I would at a minimum change the fuel filter..

 

and check the suction fuel hose from the fuel pump to the frame. if it has cracks it will let in air be for pulling fuel.