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cloudmaster_321

07-23-2023 09:56 PM

Merc 502 MPI spark plugs

Pulled spark plugs for an inspection. Lightly modded 502mpi putting out 460hp. Had NGKV Power 7 in it. Stock is AC Delco MR43T

what’s the recommendations?

Griff

07-23-2023 11:35 PM

MR43T is equivalent to NGK BR6FS(stock on newer 502mpi's).

The NGK 7 heat range is one step cooler than the 6. The 7 is probably equivalent to and AC 42 heat range.

What exact NGK plug are you using?? Are you having any issues with them fouling or ????

cloudmaster_321

07-24-2023 06:49 AM

Spark plugs

Quote:

Originally Posted by Griff (Post 4874229)

no issues necessarily. Just wanted to change them out. They have been in there for a couple hundred hours.
https://cimg6.ibsrv.net/gimg/www.off...31c484f0c.jpeg
https://cimg7.ibsrv.net/gimg/www.off...3c1209764.jpeg

Griff

07-24-2023 01:16 PM

If they have been fine for a couple hundred hours, then I'd replace with the same

shunter2005

07-24-2023 02:24 PM

Agree with Griff. You can go with the AC Delco plug as well. I prefer NGK, but my mechanic buddy installed Delco last time he worked on it.

cloudmaster_321

07-24-2023 07:58 PM

It was just interesting to me that the engine builder decided to go with a colder plug than stock. The delcos are a bit hotter.

cloudmaster_321

07-25-2023 06:29 AM

R5673-7 v-power 7 is what is in there

Tractionless

07-30-2023 10:58 AM

Careful sourcing NGK's there's alot of knock off's out there.

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