Hello David,
If the distributor is oriented correctly, close inspection of the top rim of the distributor with the cap of, will reveal a slight "slash" mark. This mark is the correct position of Number one spark plug wire with the cap installed. This "slash" is normally next to one of the distributor cap hold down clips. Looking down on the distributor cap the correct order (as on the valve cover) is 1-5-3-6-2-4 moving clockwise. I agree with Will that the tapping noise could likely be an incorrectly seated distributor cap or rotor. The distributor wires had screw on ends when new. There are different distributor caps for these W113 cars. Examine the new and old closely to determine that they are exactly the same. I believe this to be the most likely problem since you did not tamper with anything else. Good luck. Let us know what you find.
Joe Alexander
Blacklick, Ohio