base timing keeps advancing by itself...

Mark the dampener

Find tdc through plug

Mark center hub of dampener

Recheck timing

Dial back timing lights work fine, if you know how to use them.
Set the desired timing degree and then aim and adjust distributor till line shows at zzzzeeerrrrooo=0

Grab dampener by each side and turn both directions to feel for chain slop if you're curious.

Compression test.