Having pressed a few thousand rod/piston combinations in 45 years of auto mechanic and machine shop work, I've developed some pretty definite opinions on the process. Pressing works well, and, in fact, is the only way to disassemble a piston and rod combination. Each piston and rod setup takes specially-formed fixtures to support the piston properly, plus a dedicated pin pusher for each assembly. Reassembly is another matter, and most top quality shops use a heater to expand the small end of the rod, and use a preset fixture to slide the wrist pin into the hot rod. It's a one-time chance to get it right, as there's usually less than 5 seconds available to get the wrist pin inserted to the proper location before the temperature equalizes and the rod grabs onto the pin.
Pressing the pin into the rod puts major stress on the pin boss on the lower side of the piston, and usually creates tight spots that interfere with proper wrist pin lubrication. Since the average pin-to-piston clearance is only 4/10,000 inch, there's no room for error. I like the burner-type heaters rather than the electric ones, because a natural gas or Propane burner is much faster to operate. I can assemble 8 rods with the burner in the time it takes to do 3 or 4 with an electric rod heater.
Jerry
