If you can't see the mark its either....
Your piece that goes on the plug wire for the timing light is on the wrong wire
Your timing is WAAAAAAYYYYYYYY off.
Its not from the engine spinning too fast, I set the timing on my roundy round engine when its at 7 grand...and you see it plenty easy.
another thing to check...
The vaccum connection on the back of the carb that goes to the brake booster. If it is connected tight, and the hose doesnt look cracked...disconnect the hose and plug the vaccum outlet on the carb.
I have seen one or two times where the vaccum booster was sooo worn out that it caused a massive vaccum leak.