You won’t believe what fixed my timing marks problem. We decided to use a vacuum gauge to check the vacuum and the needle on the gauge bounced all over the place to where no reading was possible. We also decided to check. Compression. The first cylinder we checked (#5), was zero. We removed the valve cover and noticed one of the push rods on #5 was not positioned correctly and wasn’t moving the rocker arm at all. We fixed that and decided to adjust the valves. Many valves were off including several too tight. We adjusted the valves on all 8 cylinders. After putting everything back together, the vacuum gauge flutter was gone and we had a good steady vacuum. The timing marks came into view where they should be as well. We never thought those would be the problem.

Are You using the front Cylinder on Passenger Side as your hookup for Timing Light?

  

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For your Thunderbird, the timing marks are located on the inner belt pulley on the outer flange closest to the timing cover.  Even when new, the marks are not very legible but those marks do tend to fade away each time the damper is worked on.  The pulleys are attached to the damper hub with six rivets so assuming someone did take the pulleys loose from the damper and reinstalled them ‘one rivet off’, then the timing marks would be ~60° off.
 
I’ll suggest try timing the engine to 12-14° BTDC at idle with the vacuum advance unhooked and see how the engine responds.  Be sure to hook up the vacuum advance line once you have the initial ignition timing set.  If the engine idle picks up significantly when hooking up the vacuum line to the distributor, then that will point to some other issues that will need to be taken care of.  More on that later if that's the case as there's too little information on your engine combination right now.

Lorena, Texas (South of Waco)

Forgot to mention - you did check the initial setting with the vacuum disconnected?


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Definitely a good idea to verify the "0" TDC mark with a piston stop tool. Lots of head scratching results from trying to time engines with defective balancers. TDC is THE null point for many different checks and tune up specifications, valve timing, etc, so it pays to check this.

With that out of the way though, an engine idling in neutral has no load on it and consequently will happily run at 30+ degrees ignition advance with no problem whatsoever. (It would not be very happy if you tried to drive it).

A good check on the whole shootin' match is the mechanic's vacuum gauge. With ignition timing set to factory specification on the balancer a healthy stock engine should pull 19" to 21" at sea level. If it doesn't, find out why, because it won't run right and can't be made to run right.

As received, Damper Dudes said that my damper was in pretty good shape. Many that they receive have been pried/beaten off with a hammer, which could contribute to hard-to-see timing marks. Although it was about $50/w shipping, I used Casco's damper puller to remove mine, which probably hadn't been removed in 50 years.

Nearly invisible timing marks seem to be a common problem after a damper rebuild.  Several months ago, Damper Dudes returned my damper with the timing marks not nearly as visible as they were originally.  They were aligned correctly but had to be enhanced with a paint marker. They must leave these things in a sand blast cabinet for a very long time.   I'm sure something could be placed over the outer edge of the inertia ring or where ever necessary to protect the rolled in timing marks and not compromise the necessary cleaning/sand blasting operation.  

64F100 57FAIRLANE500

Oddly enough, I had the same situation with the timing marks, despite my enclosing a note to have them refresh the marks (which they completely ignored.  However, everything lined up ok.  I fixed the marks.
When they do a Tbird damper, as far as I can see, there is no reason to separate the pulley from the rest unless the rivets are loose ( which I regard as almost impossible happening) so everything should remain in sync.

This was damper doctor, sent it before I realized Ted preferred damper dues


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

My damper came back the same. Did the same by notching the pulley and the line on the damper. I checked for tdc with a spark plug stop and it was right on. I also painted the line and notch white. Advance movement depends on what’s in the distributor; I used a dial back timing light and as I remember the total was about 34 rev’d to near 3000. You can buy a 360* tape from speed shop but the dial back light seems to work for me. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.