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Old 07-23-2023 | 09:56 PM
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cloudmaster_321
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Default 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?
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Old 07-23-2023 | 11:35 PM
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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 ????


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Old 07-24-2023 | 06:49 AM
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Default Spark plugs
Originally Posted by Griff
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 ????
no issues necessarily. Just wanted to change them out. They have been in there for a couple hundred hours.



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Old 07-24-2023 | 01:16 PM
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If they have been fine for a couple hundred hours, then I'd replace with the same
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Old 07-24-2023 | 02:24 PM
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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.
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Old 07-24-2023 | 07:58 PM
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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.
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Old 07-25-2023 | 06:29 AM
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R5673-7 v-power 7 is what is in there
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Old 07-30-2023 | 10:58 AM
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Careful sourcing NGK's there's alot of knock off's out there.
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