Since he came to America so early, in the 1700s, chances are that he was Protestant, and that is good if you need records that early. Protestants could legally keep church records in the 1700s, but Catholics could not. Catholics did not come to America often before 1776 because there was no religious freedom in the colonies for the most part. Also, Catholics did not have the money to make the trip. So chances are your ancestor was Protestant, middle class or higher and his records would be with the Church of Ireland.
That being said, I hope the church your ancestor attended was not one that sent all it's old church records to Dublin without retaining a copy. Church of Ireland records were burned in fire fight in the Troubles that won independence for the Irish Repubic between 1916 and 1922. But many parishes kept their records or at least a copy, so it is worth a try.
Come join us in the County Cork Project as we try to find as many Cork ancestors and match them with places as we possibly can!
Sharon Troy Centanne, aka Troy-204
manager for the County Cork Sub-project