my 1966 mustang will crank but not start. their isn't a very good spark and i've tried everything.

Hi lsf1! Here's a no-start troubleshooting guide to give you and organized way to eliminate some of the simpler possibilities. Hopefully this will lead you to your problem. Hope it helps, good luck! http://www.samarins.com/diagnose/index.html

Engine timing or points and condenser are the problem. Most likely points are bad or not properly installed. Could be bad coil but that is rare.

Coil possibly but more than likely if you still have the points style distribution than that's for sure the issue. Replace with Penetronix electronic ignition for under $100 installs in like 30min and you will never have poor faulty ignition points. I did this upgrade 20yrs ago on my 65 and not one issues since. Best upgrade there is.