Im stumped, It's missing and ticking.

Does it have hedders? It may be the beggining of a exhaust leak that sounds like a ticking. The other thing that I thought of is the fuel pump actuating lever and the fuel pump eccentric, if the eccentric is wore some and it actually hits the fuel pump actuating arm then that will sound the same also and is hard to find. Just some things to check. Let us know what you find.