Flat spot on 77 quadrajet when cold

[OxonCounty77]

Got a chance to have a quick tinker with the old girl tonight,looking at the things you good folks have mentioned.

1/Realised (duh!) that the vac pipe from the carb to the valve that feeds the hot/cold flap in the nose of the air cleaner was missing. The take off port at the rear of the carb had been plugged off. A new length of hose, & the flap is held closed now drawing warm air off the exhaust manifold. Must help during the warmup period.

2/ Tried to check the ign timing following various suggestions that it should be 10 deg or similar. Have found & highlighted the mark on the damper pulley.There appears to be no mark to line it up with. I expected to see a toothed plate on the timing cover,but cant even see where one might have been/broken off etc.Nothing either looking up from underneath.The timing light seems to indicate timing is set towards the passenger side of the cover.(More or less where it is in the picture when the engine was stopped). There is a vertical ridge stamped into the cover pressing towards the driver's side,but that doesnt look right either. Any thoughts welcome.

(PS/ Santa just came to our local garden centre in Bicester Oxfordshire (England) The kiddies will get their presents super-quick this year...)