318 Engine stumble

Can I butt in?

How about this;
A) First; make sure that the firing order is correct, and your compression is fairly even, and the gas is fairly fresh, and the condenser is seeing battery ground , and that the PV is not leaking, and that the coil is seeing at least 6.5 to 7.5 volts while running; by 5.5 volts the ignition will crap out.

B) Then crank up the speed screw until it complains. Then slowly close the choke. If the engine cleans out, then you know it's sucking air,or not getting enough gas.Figure out which and fix it. But if it doesn't clean out,or gets worse; go to E); otherwise

C)To determine which is causing the lean-running, run the engine up to the crap-zone, and put a clamp on the the fuel supply line, then wait.
One of three things will happen;
1) the engine will run worse and worse and finally stall
2) the engine will start to run better as the fuel runs out, then after a long time, switch to running like #1
3) the engine will start to run better, but then almost immediately switch to running like in #1
#1 means the fuel level is too low, #2 means the fuel level is very much too high. #3 means it is pretty close, move on.

D) Once that is sorted, and it's still not right, you are gonna have to figure out how the extra air is getting into the intake.The first thing I do when I get a difficult case is to put a vacuum/fuel pressure gauge on the dipstick tube,and flip the pcv out of the valve cover, and seal the engine up tight. Then start her up and idle her up to the crap-zone again, while watching the gauge. There is no way the engine should pull a vacuum on that gauge. In fact, pressure should slowly start to build. Shut the engine off before it exceeds about 4psi, to prevent blowing a seal. If yours works like that, then you're gonna have to search harder for an external leak. Clamp or disable every vacuum line that you can find,one atta time,while the engine is idling in the crap-zone. Then move to the intake ports, then the carb base, and finally the throttleshafts. Use a checking fluid that makes a difference when you inject it directly into the primaries. I use a product called Brakleen cuz when it goes thru the combustion chamber and comes out the tailpipe it will make your eyes water and burn you nose. I don't recommend it to you cuz that's a poisonous gas, and I don't know what it will do to your brain.My brain is old so I don't care. Pure oxygen works too with no side effects,lol.
But if it pulls a vacuum,then the intake has to come off.

E1) But if it doesn't smooth out, on the choke-test;
Open the choke back up, and adjust the mixture screws to whatever she likes best,
EDIT; see post #71, for E2
And if that don't do it disconnect the Vcan.
If that makes it worse, hook it back up, and start adding timing by rotating the distributor until she smooths out, WITHOUT regard to any number, just pull on it until she smooths out.
If she smooths out, then idle it back down to 700, and now put the light on it. If the idle timing is more than 25*, you are gonna have to synchronize your piston TDC to your balancer mark.
If TDC =TDC, then you are gonna have to check your cam lobes and/or cam-timing.

F) when everything is perfect but it still wont smooth out, check that your balancer is correct for your engine,and that the TC weights are where they should be,

Tips
As to the points, If you can get 28 to 32* dwell with a gap in the range of 15 to 19, you are good at least for diagnostic purposes,so long as they break cleanly. That means the contacts should be CLEAN, flat and uncontaminated and that the condenser is preventing arcing. To prove this, you can run the coilwire to near ground, and pop the cap off. Then have a helper crank the engine while you observe both the coil wire for a steady stream of sparks, and also watching the points which should have little to no sparking.
As to the accelerator pump, you have to reset or at least check the linkage after every time you change the transfer slot opening.
As to the PV; if you have a Holley. I suggest you pull yours out and install a PV-plug for testing purposes.
As to the PCV, it should be routed to the carb base, usually the front
As to the booster, it can be routed to directly to the intake.
As to the EGR, if your manifold has a plate, make sure it's sealed.The floorjets can remain in the bottom of the plenum floor no problem.
Wires; make sure they're all fully connected on both ends
MJs, if you have headers and dual exhaust, I think those 62s are gonna be too small, but right now, they are not an issue.
That's all I got, Happy HotRodding