Please help with spark plug question on 572's
06-19-2013, 07:17 PM
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Please help with spark plug question on 572's
Have a set of 572's I'm doing plugs on. Existing are champion N9YC. They are all showing dark and some slightly wet. Called oreillys and the NGK cross comes to a resister 5 heat range plug??? Seems way too hot for my liking! Motors don't seem to miss a beat when running. No loading up it seems, missing, running hot, or blackened transom....any suggestions other than going to a stupid hot plug? Merlin tall decks, brodix alum heads. Aprox 80 hrs on motors
06-19-2013, 07:49 PM
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What's wrong with getting what's in it now? I would run a denso iridium plug with that combo. Also what do u mean by some slightly wet?? As in gas on them... U got a hot ingnition I'm assuming. If it ran 80 hrs with what's in there just fine then I would just use them. Plugs are not such a big deal to go up or down in the heat range UNLESS u have nitrous or a blower. Then u can cause prob when jumping around!!
06-19-2013, 08:29 PM
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Just seems a 5 plug would be much too hot for the constant load. I can see throwing one in a push mower but not anything performance marine....most searches on here net 9's, 8's, and a very few 7's.....much less 6's or in my case 5's. Yes some are slightly glossy....most dry black and 1 black with a slight tint of observable brown. Average plug is just solid black. Thread heat discoloration is 4 threads down. Any of you know anyone running this hot of plug in marine performance use? I wonder if these plugs were thrown in to make up for a richer mix with a lower base advance? Maybe I'm over thinking....just like to know it's close to right before heading back out for my second run. I only have had it out once thus far.
06-19-2013, 10:12 PM
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The Champion plug you pulled out crosses to a 6. I'm pretty sure a 6 comes in alot of the merc engines including hp's I usually run 6's in naturally aspirated motors. I've run 6's on 11:1 pump gas steel headed marine motors 32 degrees timing run hard for long periods of time and never had an issue. What size carb is on this thing?
06-19-2013, 10:45 PM
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They have 1050 doms. They are resister plugs so I believe they cross to the br5. I am looking up information on the rapid fire #5's as we speak (3/4" thread with washer for flat contact surface). Any word on these rapid fires? Looks like they cross to 6 ngk's. I appreciate the help
