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Popping through the carb is an indication of too much advance to start with, being the fuel is being sparked before the valve is closing all the way, and/or the secondaries in the carb are too soft and opening too much and you go lean. The Holley carbs have a secondary spring kit that will adjust the speed of them opening according to a color code. So, if you jab the throttle at idle and you see the secondaries move more than just a hair, spring is too soft. Additionally, the squirter, if too small a number, or if the accelerator pump is too loose (that little arm that goes from the throttle shaft forward and operates a little arm on the underside of the carb bowl, there is a 3/8ths (I believe) bolt, spring and nut. It should be adjusted so there is zero play, but no pressure when touching the arms at all locations.
Just to check here, you say 318, but is the intake manifold a 318 intake? They do make them, the 340 and 360 intakes have a difficult time sealing properly if at all because the ports themselves are too small for the gasket of the 360 and vice versa. The gasket kits have both gaskets, a comparison is noticeable and can cause some of these idle problems, work their way to throttle stabbing stumbles and popping, too.
The distributor, as others have said, would be best converted to electronic ignition, it is much better than points, you may have a worn bushing that is also allowing the points to bounce and change as you stab the gas, altering the points setting. You can pop the cap and see if you can push and pull gently side to side on the rotor to alter the points setting to verify this slop, there are several companies that offer aftermarket electronic ignition systems. Inside the distributor, under the points plate, are the mechanical advance counterweights and springs. Too soft of springs will advance too fast, there are spring kits to adjust them, and then the vacuum advance canister may have an adjustment to it, I believe it is the vacuum advance canister that has a hex on the end of it, not just a round cone. If it does have the hex, you can stick a long allen wrench that fits into it and crank up or down the amount/speed of vacuum advance. clockwise should reduce it, counterclockwise should increase the amount.
A lot of adjustments and checks, but start with 8degrees BTDC, pinging and popping is an indication of too much advance, not too little, and too much advance is not necessarily a good thing. Once everything is dialed in, a simple two degrees of too much advance can drop gas mileage by two miles per gallon, and hurt performance. The key is the mechanical advance tuning to get it correct.
Keep us informed of the results and findings.
Just to check here, you say 318, but is the intake manifold a 318 intake? They do make them, the 340 and 360 intakes have a difficult time sealing properly if at all because the ports themselves are too small for the gasket of the 360 and vice versa. The gasket kits have both gaskets, a comparison is noticeable and can cause some of these idle problems, work their way to throttle stabbing stumbles and popping, too.
The distributor, as others have said, would be best converted to electronic ignition, it is much better than points, you may have a worn bushing that is also allowing the points to bounce and change as you stab the gas, altering the points setting. You can pop the cap and see if you can push and pull gently side to side on the rotor to alter the points setting to verify this slop, there are several companies that offer aftermarket electronic ignition systems. Inside the distributor, under the points plate, are the mechanical advance counterweights and springs. Too soft of springs will advance too fast, there are spring kits to adjust them, and then the vacuum advance canister may have an adjustment to it, I believe it is the vacuum advance canister that has a hex on the end of it, not just a round cone. If it does have the hex, you can stick a long allen wrench that fits into it and crank up or down the amount/speed of vacuum advance. clockwise should reduce it, counterclockwise should increase the amount.
A lot of adjustments and checks, but start with 8degrees BTDC, pinging and popping is an indication of too much advance, not too little, and too much advance is not necessarily a good thing. Once everything is dialed in, a simple two degrees of too much advance can drop gas mileage by two miles per gallon, and hurt performance. The key is the mechanical advance tuning to get it correct.
Keep us informed of the results and findings.
