1/16th of a turn past finger tight is all it takes for tapered seat spark plugs. If you broke them, you were trying to over tighten them, or, you weren't using the correct tools.
It was an odd angle with the AC compressor in the way of the front pass plug. I broke 2 off near the top trying to put them in. That said I got them in a little tighter then what you suggested here.
There are 2 ways to snap a spark plug, one, the socket isn't on all the way, and angled, or two, over tightening them combined with one. All you need is a flex head ratchet and a short and long extension. Yes the A/C compressor and air box get in the way, but it is entirely doable with a little experience. I'm sure you put the plugs in too tight, which increase the chance that you will break them trying to take them out.
Well I did get it in the 3rd try. Knowing what you said about how tight they should be mine are in a tighter but I did not jam them in full force tight either.
I broke just the one. It was because when I went to tighten it down the ratchet/extension combo was not straight with the plug and when I went to tighten it the top of the plug snapped off.
