1968 289 Carb Replacement?
Hang in there. This will get fixed. In my opinion you are on the right track.
The bowl overflowing indicates 1 of 3 possible things.
1. - The needle and seat and stuck
2. - Float has a hole or is filled with gas
3. - Float level is not set right
Should be pretty easy to check things out.
What I would do....
1. -Try once more to adjust the float level. To be sure you are doing it correct, let's review. Put a 5/8 wrench on nut B, place a screwdriver in lock screw. Try turning the wrench clockwise as you turn the lock screw counterclockwise. You just go a tiny bit, enough to take the force off the lock screw. I would remove the screw and washer.
Next I would unscrew the whole needle and seat assembly by backing it out of the carb. Spray the needle and seat with a carb cleaner or starting fluid.
Now I would install the needle and seat and screw it in to the carb so that just enough of the top threads are sticking out and you can still get the adjuster nut on.
be careful there are 2 thin washers. Put the locking screw back in and while holding the wrench on the nut, tighten the screw. Right now, your fuel should be pretty low in the bowl.
I You may or may not know how to check the bowl height so I will explain.
See the brass screw...sight screw.
1. - Shut off the motor,
2. - put a small container under the screw to catch gas
3. - Gently remove the screw. (CAUTION) there is a thin metal washer behind it and the screw is brass (soft threads)
4. - If gas pours out of the hole, the floats are too high or the needle and seat are sticking
5. -If the gas doesn't pour out, that is good. You want to push down on the fender and let it bounce up. (shake the car). If the fuel level is correct, the gas should just trickle from the hole when the car is rocked
Now I this doesn't fix the problem, I would take off the bowl.
Check to see if the float feels hollow. Shake it. you should be able to tell.
If it is great.....pull the needle and seat from your old bowl and put it in the new.
The repeat the process of adjusting the bowl height.
Remember, a pretty good starting point is to have about 1/8 of an inch of the needle and seat assembly above the surface of the carb.
You are getting close. Naturally, when the car starts....give your grandpa a big hug and thanks. Print Dad