Hi everyone, my question is simple how can I set my ignition without any marks on the vibration damper? And without removing the head of course...
How can I know it's the TDC?
Thanks for your help

Marc

Theres a notch on the rim of the dampner - yours may be coverd up or dirty? I believe its 5 degrees off of the crank key unles your dampner slipped. Once you find the notch, paint it with whiteout or yellow marking paint.

Then take #1 spark plug out, put your finger where the plug would be and have someone bump it over or do it with a remote starter switch. You will feel the air pressure escape, and keep turning till mark you made on dampner reaches the 0 on the timing tab.

Hi Pierre and thanks for your answer but here's the point : how can I do without this notch? My tab (attached to the engine) seems to be way off and the damper may have slipped in 30+ years of abuse...

Without marks you will never be able to accurately set the styatic timing. You should thoroughly clean the timing tab and the dampener to make sure the marks truly aren't there, and if not then send the dampener out to be rebuilt.

ALternatively, a method to get a truly ballpark figure would be to remove the #1 spark plug and valve cover and turb the engine over by hand until it gets close to TDC on the compression stroke. Stick a coathanger down the #1 plug hole and feel it as the piston rises. Once the piston stops rising in the bore and starts to decrease you know you have hit TDC. Get some whiteout and mark the dampened next to the 0 degree mark on the tab.

Another way is to just set your base timing for maximum vacuum at idle. If it is hard to start then back it down a few degrees.

Well you can still do it with the remove the plug and use your finger method, you just won't be as precise. Keep going until you don't feel any more pressure on your finger.

You can feel for the key with your finger on the inside of the dampner and make a mark that way to get you close.

But with your 30 + years of abuse and suspected slippage, chances are your timing chain stretched or jumped a tooth if you suspect timing is off.

If you feel that the dampener has slipped, swap-on a good used one or have yours rebuilt. ( I have used ones if needed)

I see many "no mark" Slants as a result of using the wrong timing chain cover with the wrong dampener.
60-67 engines had a bolt-on timing tab (mark) viewed from the driver's side, 68 and up had a tab welded to the T. cover, viewed from the passenger side. Mix & match parts don't show a mark when viewed with a timing light.

I can quickly find TDC by using the 'positive stop' checking method.
I have a piston stop that screws into the #1 spark plug hole.
SLOWLY bring the engine around (with a wrench) until it hits the stop, mark the dampener at the timing tab's zero(0) line. Rotate the engine the other way until it hits the stop and again, mark the dampener at the zero line.
Carefully measure the space between the two marks you just made and exactly 1/2 way between these two marks is TDC. Punch a new reference mark at this place.
DD