Why does the 2.9L v6 tick in my 87 ranger? and what makes it tick?

• The noise is probably collapsed hydraulic lifters.These engines are well known for their lifter noise. It's typically caused by insufficient oil pressure in the lifter galley. Many people have seen evidence that these engines were originally designed for solid lifters and were retrofitted with hydraulics for the U.S. market. The oiling system feeds all the galleys with full oil pressure all the time, even the rocker pedestal oil galleys that feed the rocker shafts. The oiling system is taxed in keeping the lifters pressurized even in a new engine, so the engine not being very tolerant of wear is a primary issue. Try using Shell Rotella 15w-40 to sustain oil pressure as long as it's not excessively cold outside.
• Other than the Rotella, new rocker shafts and arms can be tried as they are fully pressurized and can leak pressure. A high volume pump with new pickup can be tried also but if engine wear is severe neither will substitute for a total overhaul or replacement engine.

Most likely a lifter, usually caused from low oil and infrequent oil changes