I have a 79 GT4 Bought the car last fall - put 700 miles trouble-free miles on it before putting it away for the winter. Did timing belts, shims, seals, coolant hoses, fuel lines, carb rebuilds, plugs, wires, cap rotor. Car has twin distributors with the electronic ignition. I set up the timing static at the 7 degree advance on both banks. PM1-4 and #1 on the mark; PM 5-8 and #5 right on the mark. Car started right up on Sunday and ran OK, but had an oil cooler leak. So change that out, and start it today to start zeroing things in. Got out the timing light and so began my issues. I cannot see the timing marks, and the timing seems to move all over the place. Plus my tach (and the tach reading off of the timing light) are reading 2X engine speed. I verified this with an optical tach on the harmonic balancer with a reflective strip (engine at 900, tach says 1800). The engine backfires out the exhaust, but not consistently (carbs are admittedly not set up yet). I can see sparking inside the distributor cap through the little vent holes - that does not seem normal. I did not mess with the distributors at all over the winter - just removed, stored, and reinstalled per procedure - while adding cap, rotor and wires. I have verified the firing order and the ignintion static timing again - AOK. I was thinking its a bad ignition module, but that usually shows up with a tach needle jumping (at least that's what Ford's used to do...) Ideas? I would hate to start throwing parts at this problem, especially since I don't know where to get a module or trigger parts anyway...
