Need help, 67 Camaro with rhs 502

[sic7camaro]

Checked the crank timing and it’s at 13 degrees so I’m really lost as to what’s causing this problem.
I forgot to mention before that it doesn’t do it every time either, sometimes it fires right up.
If anybody has any other ideas as for what’s causing this, I would really appreciate the help because I am at a lose with this thing