I just got done rebuilding my engine with a 306 cam on my 96 camaro and my opti just started acting up which I am not sure if the previous owner ever replaced it. Now the engine has 150000 miles before I rebuilt it and I am not sure if it is just time to replace the opti, but before I do replace it I had noticed a slight circle, hard to tell if it is actually embedded, but there is a circle that is noticable because oil couldn't get under the dowel pin. Is the pin even suppose to touch the back of the shutter wheel or not? Thanks for any help.

 

The pin should only touch the sides of the slot it rides in. The end of the pin should leave no mark on the opti (that would indicate the pin was too long). Comp dowel pins should be checked for proper length. They have a tendency to be way long.

Example:

 

this image was really useful thanks man!