Poping 258 engine Any suggestions

[Teamamc <teamamc@xxxxxxxxxxx>]

I have an 81 Concord. 258 auto air.
At Idle the car gives off a poping sound through the carb.
If I pull number 6 wire the poping goes stops.
If I put the wire back on and rev the engine the pop turns into a violent
bang through the carb.

I have changed plugs wire cap and rotor.
Adjusted timing. Compression is 145-150 across all cylinders.

It appears to be timing but I can't figure out whats left.
no matter where I put the distributor the pop is present.
With all 6 wires on the engine will idle.
As soon as you pop it in to gear the engine bangs and stalls.
If I remove #6 wire  I can put the car in gear and drive it.

Any Idea's.
I am stripping the car but want to make sure the engine runs well before
pulling.