Pull the carb off,empty it, flip it over, using the speed screw adjust the transfer port exposure to a little taller than wide. Reset the mixture screws to 2.5turns out.Next; prove you got the right base gasket, prove the manifold mounting flange is not cracked, and prove you can marry those two without a base vacuum leak. Then,flip the carb right side up, bolt it back on,and check/adjust the fuel level to the factory setting.If the manifold has EGR provision, make sure it has been defeated.Finally,fill the carb up thru the bowl vent with about 50cc gas.
Next;defeat the vacuum advance for now and make sure the PCV is hooked up properly, After this, do not touch the speed screw;instead,adjust the idle speed with timing and idle air bypass. 18* initial is about right. Maybe a little less.
Now;Start her up!
The very first thing you gotta do is make sure the power-valve system is not activated. That carb came off an engine that was probably pulling more than 18 inches of vacuum so it will have a pretty strong spring activating the PV or metering rod's power-piston. Your 284/484 is gonna be down around 10" or less, so as far as the PV system is concerned, the engine is working pretty hard and the PV could be a good ways open. If it is,then it's gonna be your job to re-calibrate it and make sure it stays closed at idle. And don't be clipping coils off the spring;that will really mess things up. Go find a similar spring with less pressure and clip coils off that one until it is the same length,then recheck it's calibration. Or just for testing purposes, pull the spring out of service, until later.
OK so once the PV stays off/closed at idle,then;
If the idle speed is faster than 750/800, even with the initial timing retarded to as little as 14*, then go look for a vacuum leak including sucking from the crankcase. Find it and fix it. If the vehicle has a brake booster,prove it's not leaking or defeat it for now.
But if,as I suspect, the idle speed will be lower than 750/800,then you will have to provide additional air around or thru the throttle valves; do not use the speed screw. You can figure out how much more air to give her,by introducing a calibrated leak into the PCV system. I just drill a hole in the top of the plastic PCV. Once you have her up to 700,then fiddle with the Mixture screws for best quality idle. Then figure out how far out they are,.You want them to be about 2 to 3 turns out. If they are less than 2, then close the throttle with the speed screw up to 1/2 turn and reset the mixture screws. But if the mixture screw are out more than 3 turns then open the throttle with the speed screw up to .5 turn, and reset the mixture screws,back to 2.5
Now, try putting her into gear and see what happens. The idle speed should not drop more than about 100/150 rpm. If it does, check the idle timing. If it is less than 18* add 2 degrees and try it again. If it still drops too far, add 1/2 turn to the mixture screws, and try again. If it still drops too far add 2 more degrees timing. If it still drops too far, then, STOP. Open the throttle 1/2 turn on the speed screw, and return the mixture screws to 2.5 turns. If the timing is more than 18* put it back to 18*. Now check the idle speed. By now it might be over 750. If it is between 750 and 850, put it in gear and check the Rpm-drop. If it is more than 100 but less than 150, and the idle quality is good, then you are done.
Now we have to make permanent the idle air bypass that you introduced to the PCV system. Simply measure the size of the hole, and calculate the area, divide it by two, back calculate the size of the hole to make this new 1/2area, and that is the size of the two new holes you are gonna drill in the butterflys, one in each.If you have a choice between two hole sizes, then opt for the smaller of the two. Put each hole on the front half of the butterfly,about half way between the idle discharge ports and the transfer slots, AND at least 1/4" away from the edge.The exact position is not critical,so long as it's not under one of the discharges. Chamfer the holes, both sides of the valves, when you are done. Yeah you have to take the carb off and drill from the underside. Don't forget to plug the test hole in the PCV valve.
Now you can restore the booster into operation, but it's still too early to reconnect the Vcan
Now it's time to;
A) limit the power-timing
B) install a preliminary curve
C) if you removed the power-piston spring, reinstall it and calibrate the PV power piston as to it's rate and timing.
D) reconnect the Vcan and calibrate it.
