Classic/Antique Car Repair: Timing, vacuum leak, ford custom

Question
ok so I wiped off the dirt from the vibration Dampner and found the degree marks for BTDC, but I can't find the mark that stays stationary so I can use the timing light on it. I don't think it's crossed wires, I changed them about two months ago and pulled them out and replaced them one by one. it was running fine since, but for the past two weeks I couldn't even take it to school it lost so much acceleration and power. well back to the question. where would that other mark be for the timing. and also in which direction do you retard and advance the timing?
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The text above is a follow-up to ...

-----Question-----
ok I have been experiencing backfiring and a dramatic drop in power and acceleration in my 1966 Ford Custom 500. I checked the points and I re-gapped them, it helped but still it was back firing through the carb. I found a vacuum leak on a tee to the intake manifold, one side goes somewhere to the tranny and the other goes to the brake booster. anyways i asked around and I have gotten the response that it's timing. I can't find the timing marks though. I found the degree marks but can't seem to find the other mark to time it. I really appreciate it.    ~Matt
-----Answer-----
Matt;
Hi did you wipe off the area as it could be full of dirt.  did you check the plugs and the wires for a crossed one. it could also be a valve or rocker , lifter, check the plugs if one is bad than you will know what cyld. it is. but the timeing marks on some are hard to see I put white marker on them to see them better.ok  >>>also the vacume line must be hooked up or pluged up.

Answer
Matt;
Hi   ok you found one any way , did you look good on the block , etc. as far as the dist. if you loosen the nut so you can turn it  , if you turn it fwd. you should hear the engine rev,. higher thats  advancing it , what you could do is to try it by ear, just move it up a very  small amount just so you can hear the motor rev. than tighten the nut down than try it.  but the vacume leak  must be fixed if it has not been.  look good for the tim. mark as it might be just a  point  or small  line. ok first, mark the dist. with a marker and also on the block or firewall where it is prior to moving it, this way you could put it back in the same spot if it did not help.