We installed a used engine that and after install it started but the water mixed with the oil. I took the head off and had it checked along with a valve job. Put it back together and now no spark.
The distributor rotor is turning, we have power to the coil and no spark.

What are your thoughts?

Check for spark at the coil - if you're not getting a spark there you most likely have an electrical issue, if you have a spark there but not at the plugs, the distributor is probably installed incorrectly.