Set the #1 to TDC and remove the distributor cap. The rotor should be pointing DIRECTLY where the #1 plug wire attaches. What you are experiencing is caused by the spark from the rotor being redirected to another cylinder instead of the one your timing light is attached to. That may also explain some of the poping you said you are hearing. Just reset the distributor. You may have to turn the
oil pump drive to allow it (the distributor) to drop ito the correct spot.