A sound like trailer chains dragging. Check the heat shields on the exhaust system for loose or missing tack welds. Fords are notorious for this and have been since the inception of catalytic converters.
Check the timing. Make sure it's set right and advancing properly under acceleration/load.
How regular is the sound? Does it sound rhythmic or is it random?
Wednesday, June 15th, 2011 AT 4:48 AM