I'm late to the party but I have a quick story about this to reinforce the point. Many moons ago when the earth was young and dinosaurs roamed the earth, I was changing spark plugs on my XJ-6 and did not realize that the tip was a separate part in the spark plug box that threaded on so you could use spring clip or threaded cables because I'd never seen that before. Since it was way easier than leaning over, I was sitting on top of the XK to remove the plugs, and when I opened the box, the loose tip bounced a couple times and went right down the open spark plug hole. The tip was non-ferrous so I could not fish it out with a magnet, so I used a butterfly closure and stuck one side of it to a long Philips, then fished with the sticky flap dragging on the top of the piston until I caught and extracted the tip. In other words, magic.Vic Skirmants wrote: ↑Tue Oct 29, 2019 7:36 am Ken; and EVERYBODY else; When assembling an engine, or anytime the intake ports are "naked", keep shop rags or paper towels stuffed in the ports. You never know when a stray SOMETHING might find its way into the port. I have an interesting story about that from 40+ years ago. Too long to post here.
So... cover the openings. Blue painters tape or better yet the green 3M paint masking tape are what I use most of the time unless the part is greasy, then a rag.