Re: What kinda spark plugs
AC-MR43LTS or NGK BPR6EFS<br /><br />this is out of mercruiser service manual #26, for that motor.<br /><br />they are standard plugs (all plugs are the same really) and can be gotten/ordered from most part stores.<br /><br />Cross reference would be a resistor plug that has 14mm threads, 0.708" reach, and the coldest or next to coldest heat range.<br /><br />I think the Bosch equivalent, according to my NGK cross-ref table, is HR8DCX stock #7571. From there you can get to finding the platinum versions if you care to.<br />Some others are Autolite AR103, Champ RS9YC stock #304.<br /><br />NGK TR6 will work, they are more common, but I've called NGK and couldn't get a definite where their heat index is compared to the BPR6EFS. They seemed to run a little hot in my 3.0L but that was back when I had carb problems, and I haven't tried them since. My recommedation is to stick with the AC's, they are a good plug, easy to get, and should only be $2 each. If you try other than the AC delco's, be sure to check them frequently for signs of running too hot.
