Are the AC MR43LTS copper core? It would seem the OEM plugs for his 4.3 are factory platinums based on the part number he gave. In past research on this topic for vehicles, this was the summary of how I understood it:
- copper, produces better spark but lasts a shorter time before needing to be changed
- platium, not a "peppy" but lasts 3x longer than copper
- iridium, best of both worlds providing better spark than platinum but lasting longer than copper
Not being snooty, really wanting to learn because I too need to change the plugs and have never been a fan of platinum in anything I ever tried them in. But when I worked at a parts house a long time ago, I recall all the people who ran cheap copper plugs instead of the recommended OEM GM platinums who came back later because they burned up so fast...it made me wonder if there was something "different" about the ignition systems of vehicles that they chose to use platinums in? I doubt it on a boat but you never know; then again boats don't get as much use as cars so prob wouldn't matter as much.
