There are three things you need for an engine to run
Compression, spark "in time" and fuel
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COMPRESSION
Have you checked compression? Are you CERTAIN the valves are properly adjusted? How exactly did you adjust them? (I'm assuming since this is a 273, it likely has adjustable valves and may be a solid lifter cam)
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TIMING
You likely have the distributor 1/2 turn off
You need to learn to set up the distributor. This is a very basic, but very easy procedure once you really learn and understand. Try this:
http://www.forabodiesonly.com/mopar/showpost.php?p=1969972787&postcount=22
So if you read that and are totally confused, try this:
There are two ways to initially install a distributor and know that the timing will be close
A--IF the valve covers are off, bring the timing marks up to about 10BTC and look at the no 1 and no6 valves. One cylinder will have both valves closed, the other cylinder will have both valves open by an approximately equal amount. If both no6 valves are closed, install the distributor so the rotor points to the no6 plug wire tower. If both no1 valves are closed, install the dist. with the rotor point to the no 1 wire tower.
B--The second method is to remove the no1 plug, stick your finger in the hole, and bump the starter. You may have to "go round" a couple of times if you haven't done this. When you feel compression on your finger, look at the marks, which should be "on their way" up. Wrench the engine up to 10BTC or so. This IS no1 "ready to fire." Install the dist, rotor pointing to the no1 plug tower
Now, you need to set the timing. Set your vacuum advance in a "good" position, IE room to swing it a little, and look where the rotor points. Look at the breaker points, and use a light hooked to the coil NEG terminal (distributor). Turn the key to run, turn the distributor clockwise some to retard the timing. This is to "get slack out" of the mechanism. Now, slowly rotate the dist CCW until the light turns on. Snug the distributor clamp down at that point.
Check the cap, the rotor should now just be "coming to" a plug wire tower, and this is your no 1 wire postion
If you follow this carefully and do so correctly, the ignition timing will be close enough that the engine will fire and run WELL
You can ALSO check timing "on the starter" with a timing light. Just hook the light up as if the engine was going to run, have someone twist the starter, and check the timing at the marks.
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FUEL
I would temporarily abandon the fuel pump issue, and SAFELY rig a container of gas up above with a siphon hose into the carb inlet. This will give you clean fresh fuel and a known good supply of fuel. Of course you need to plug the outlet from the engine pump.
The old tank may have several issues, including............
Gummed up filter sock in the tank pickup,
rotted collapsing rubber connector hoses at both the tank and the pump inlet
gummed up fuel line front to rear, or even rusted through (pinholes)
bad fuel pump
and of course old fuel
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