Whilst trying to time my car I noticed something quite strange.. I've got a 1967 straight 6 194cid on a 2 spd powerglide. I idled the car at exactly 500rpms pulled the distributor advance hose off and plugged the vacuum line. Aimed the light at the mark and saw it crawl up from the right and disapear over the left side.. After like 10 minutes it showed up again.. Its rotating counterclockwise. I tried moving the distributor and although it moved the mark left or right the mark still kept moving around by itself continuing its gradual rotation.. Do I have a vacuum leak or something somewhere?? Dirty carb, bad carb gaskets? Bad plug wires?? Where should I be looking I know this aint normal. I hooked my vacuum guage to the distributor hose to plug it.. I dunno if that makes a difference.. I don't think a vacuum guage leaks air into it.. This is so weird.

Sounds familiar to me. Check your balancer.The ring has seperated from the core that connects to the crankshaft. Ask me how I know! You will need to get a new balancer.