RE: sts 28 starting problems
How much fuel has been run through it and what fuel are you running? 270 is not all that hot but is at the upper end. Do not run an OS plug as OS plugs are short plugs and STS engines take the standard long plug. Have you checked the head shimming after break in and re shim as needed? I have run hot plugs in my STS engines with 30% fuel with out a problem so a McCoy 8 or 9 should be OK.