If your careful and don't drop the small clips, you can do it on the car, only have to remove the "Top" airhorn assembly from the carb. Otherwise remove the carb from the engine, and take it apart on the work bench, if you remove the carb, you can reuse the carb base gasket.
I lay all the parts out on fresh clean paper towels, maybe 2 or 3 paper towels all connected together. I lay the fasteners and other parts removed out all in a row in the order I removed them. I make a big zig zag row of parts that snakes back and forth on the paper towel. When going back together just follow the order in reverse.
Details include:
There are 2 or 3 links that connect the accelerator pump and choke that need to be disconnected. Real small clips hold the links, I use a needle nose pliers.
Next I remove the air cleaner stud, a pair of pliers, grip the stud tightly and it will turn out of the carb base assembly.
Next remove the two small covers that hold the metering rods in place. These covers have a torx screw, so you may need to buy a cheap set of torx drives. I only run the torx screws out far enough to be able to rotate the cover out of the way, a small screw driver helps rotate the covers, and helps lift the metering rod/piston assembly out the carb. There are springs under the pistons, take them out too. Write down the part number of the metering rods, and note the color of the spring for future reference.
When going back together, before installing the metering rod assy, spray some Gumout brand carb spray into the small brass tubes that are under the metering rod cover.
At some point during the rejet is a good time to clean the carb idle mixture screws and ports. Turn the screws in one at a time clockwise, counting the full turns, half turns, and quarter turns it takes to GENTLY bottom out the screws. DONT tighten them, just gently seat them. For example you may turn them in 1 and 3/4 turn to seat them. Once you know the turns in to seat the mixture screws, then you can turn them all the way out, clean the screw and hole, then run the screw all the way back in to gently seat, then turn each screw out the 1 3/4 turns, which puts them right back where they were to start with. Take the two idle mixture screws out and spray carb cleaner down the screw holes, wipe off the mixture screws,and reinstall them. The two mixture screws should be very nearly the same number of turns out. Tuning them is a whole discussion in itself.
Now take all the long screws out that hold the carb top (air horn assembly). Be real careful that the airhorn gasket comes with the airhorn assy, use a knife to reach in and carefully cut the gasket loose from the carb base assy as you lift the airhorn assy. Lift the assembly straight up, the floats will come with it, and so will the accelerator pump. Turn the airhorn assembly over and set on a clean paper towel. Nows a good time to verify the airhorn gasket is not damaged anywhere, you can see all the gasket with the assembly turned over.
Look into the carb base assembly, you will see the fuel sitting in the float bowls, and see jets at the bottom of the fuel. The jets toward the front of the carb (choke side) are the primary jets, the jets to the rear are the secondary jets. Use a screw driver that fits the slot in the jet correctly, meaning not too loose and want the screw driver to contact the entire slot in the jet, not some too small screwdriver that bearly catches the notch. Turn the jets out, they are only tightened snug, not jambed in place like your mad at it. There is a part number on each jet, write the number down for your notes. Also write down the accelerator nozzle size, it is stamped on top of the accel nozzle assembly.
In the float bowls, there will typically be some dirt/sediment in the bottom of the bowls. Use paper towels to wipe out all the debris. Before putting the airhorn assy back on, pour some clean fuel into the bowl to about the level that was in them when you started wiping out the crud.
Use the Edelbrock tune up book that came with the carb to pick a new jet size, if your rich typically go 2 % lean power and 2% lean cruise to find the new jet size. This may include a metering rod change.
Assemble in reverse order. I reuse the gasket between the carb base and airhorn, just don't break it when removing the airhorn assy, If it breaks anywhere, then it must be replaced.
While your at it check the float settings. I also installed the "off road" needle and seat assemblies that the float pushes against, they help prevent excess fuel on bumps and hard cornering.
On a 440 dodge I followed the book recommendation for altitude compensation, worked out real well with 2% change for 3400 foot elevation. On a high compression Ford 410 being used above 5000 foot elevation ended up running even leaner to get the carb mix correct, and ended up using Edelbrocks O2 oxygen sensor to fine tune the carb. Worked out real well. Both of these were cast iron heads and intake manifolds with exhaust heat thru the intake manifold heat cross over.
Take your time, and allow plenty of time. Do the job out of the wind, scorching sun, and foul weather...save the extra beers for when your done and have it running again. you should do fine. hope this helps.
