Has antone used Bosch Platinum+4 plugs in a 502 mag? I have a MSD ignition and would like to try them this spring. Anyone know the AC MR43t equal.
Thanks

TopTrim;

I don't have an answer for your question, but maybe you can answer a question for me. Your post indicates that you are running an M.S.D. on your 502. From your profile I got info. that your boat is a 2000 model. So, it obviously is an MPI motor. Anyway, I just put an M.S.D. 6M on my '99 454 magnum motor. I haven't started it yet, it's still winterized. The question is , in the wiring diagram M.S.D. makes mention that in SOME CASES you need their tach adapter to get the tach and injectors to work. I called M.S.D. tech line and asked what SOME CASES means. Their answer was " Your motor PROBABLY doesn't need the tach adapter " I asked how probable probably means, they said they weren't really sure on marine engines. Real good help !! Did you have a problem with your M.S.D. or did the motor fire right up?

Thanks

I didn't need the tach adapter. Everything works fine.

Thanks toptrim

I use AC Rapid Fire #1 . I have a 502 efi motor works great with them. Plus they will not rust out on you.

Hey how often do you guys change spark plugs??

27 fountain I change them every season

I have 502 Mag MPIs and once a season the engines get new plugs, distributor cap, and rotor.

On a boat your generally going to change the plugs more often than needed anyway (for safety, & performance concerns) So DON'T waste your money on platinum plugs, the only advantage to a platinum plug is that it lasts longer, it actually doesn't conduct spark as well, so there is no advantage to using them !!!

I agree with RumRunner, platinum plugs are a waste of money in a marine application..they're for 100,000 miles before tune up auto engines. When the racing circuit starts using platinum then you'll know its better....I had a 625HP 502 Mag Natural asp. in my Baja and ran MR43T's, they worked fine.