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Barry Eller
02-22-2007, 06:17 AM
I'm currently using AC MR43T plugs in my 502. This is the plug recommended by OMC for use in the original 454 HO. The OMC manual also recommended the same plug for their applications using the 502.

I'm not having problems with plugs with the new MSD Ignition, but was wondering what options are available.

ThunderMarineDave
02-22-2007, 11:09 AM
The comparable NGK plug is the BR6FS - stock item at most marine dealers.

I have had best luck in all vehicles with NGK plugs - I have dyno results testing the 6 top brands, and NGK did best (52hp in my 500cc motor), most were about 50hp, Splitfire was noticeably worse at about 48hp.

-David
THUNDER MARINE
800-984-3098

Pismo
02-22-2007, 01:35 PM
Are those NGKs extended tip like the MR43TS?

Thanks

MOP
02-22-2007, 02:49 PM
The 43T's have more then proved them selves over time, I have seen many othters tried none to my knowledge none has done any better. Not to say many do just as well but the 43's track record can not be beat.

BigGrizzly
02-22-2007, 06:40 PM
I'm sponsored by NGK, so i like them but unlike Thunder marine I never found that kind of HP difference on the dyno if everything else is correct. In my Criterion I use autolite and don't have a problem but I do have a little more HP than you. As for the splitfire plug it is just a gimmick, spark always jumps the smaller gap, same with the Nipon denso HOT U plug which are pron to fouling. My recommendation is use what works. On your motor you arn't going to get any gains, if what you have works well.