engine is missing really bad when idling.

[tomkatesam]

I have 1975 merc 850 and i just replaced the timing belt because it was really cracking. I put the flywheel back on but mark wore off, so i used a screw driver to find tdc and it seems like i did but when i line the arrow (on the dist.) with the 3 dots on the flywheel the engine revs to high so i have to set the arrow to the left another notch. Know when the engine is idling it is really ruff and is missing really bad. I have to increase my idle to 2000rpms just to start the engine. Should i go and buy a timing dial or could it be something else. thanks everyone for your help on the forum, TOM