Engine Knock Ping Might be trouble

[dr_ws6_00]

Just inherited a truck, it hasn't been fired in three plus years. Its a 76 Ford f-250 with a 390. the engine only has 3000 or so miles on it and it knocks at idle and pings when im accelerating up a hill. At first i didnt hear the knock but it made alot of noise like an exhaust leak i tightened the headers and that didnt seem to help. I had to drive it home on the interstate for about 500 mi. the exhaust leak sound has almost gone away but now there is a knock when its idling, and makes noise like its pinging or has alot of sark knock when im going up a hill. It doesnt vibrate that much and when gpa had it rebuilt there were no mods. Not really sure what to do next. ANY input would be greatly appreciated.

[nhraformula]

sounds like the car needs a tune up being that it wasnt fired in 3 years

[dr_ws6_00]

I changed plugs and wires, rebuilt the carb, changed oil, antifreeze and thermostat, belts, fuel lines, vacuum hoses and new fuel filters. Is there anything else you would reccomend doing

[Johns00Z28]

How long had the fuel been sitting?

[wnmech]

Check ignition timing. You may need to retard timing. Try premium fuel and see if the pinging stops that would be my first thing to try.

[dr_ws6_00]

I drained the old fuel out and put new in, since its old i put lead additive in it ive played with the timing and no results. could it be possible that a lifter collapsed? thats almost what it sounds like. a really loud tapping noise.