Set timing

If the light bounces and flickers it is caused by either a balight or a misfire on the cyl. Move the pick up closer to the distributer and see if that helps. That is a good engine set up.

If you have a mid-late 60's 327 your initial timing is 4 degrees before TDC. This info is on a 68 327 out of a camaro with eithier 275 or 325 hp motor. If you have a bunch of marks on your balancer you need to find TDC and then put your own mark on it and time it from there. You will need an indicator to put in #1 plug hole then turn motor-by hand- until piston meets the stop then mark that on balancer, then go oppisite direction until you reach the stop that way, mark spot and true TDC will be exactly in the middle of the 2 marks. You should be able to time from there. Chevy sb balancers have been known to have the outer ring slip and shift on them so sometimes the factory mark may not line up correctly. But you still need to get the light hitting right, too. Hope you made some sense of this, it's early and the coffee hasn't kicked in yet :shock:

Burrbrian is correct about the marks. The rubber between the balancer portions does fail. I read the post as a timing light issue with the mark bouncing because of eratic operation. PLease clarify EXACTLY what problems you are experiencing and either of us can help you.