Re: Proper spark plug gap
On the subject of plugs, and gap... Wondered if I could get an opinion on this: Was told I could use basic rc12yc
copper plugs and gap them at .044 with the thunderbolt ign, and pick up a few hp's. Being the older softer copper, they would need to be replaced more frequently, but are supposedly more conductive, and extend deeper into the combustion chamber for a better burn. Anyone ever hear of doing this?
Since this is an opinion I'll offer mine
My buddy has two 454HO which state on the covers to use NGK platinum plugs. The starboard engine is original using NGK with 500 and some hours. The port engine is being replaced for the second time and it had higher heat range plugs then Merc specified. The new engine has the NGK plugs as specified and gaped at .035.
My 1994 Formula had a 454 and I changed it out for a 502. The 502 is uses MR43T and needes to be replace every other year or the engine will have trouble with carbon build up. Engine hours showes 535 or so hours and the 502 has aboout 300 and some hours. Replacing plugs every other year fixes the issue, no one has offered an answer as to why.
My 1995 rinker has a 454 and has never had the plugs changed and has always runned great. The boat has 636 hours and has Champion RV8C plugs installed (covers say MR43T and I bought the boat new) and they look pretty good, no carbon build up.
That being said use any plugs you want but
Do Not use plugs out of the heat range specified by the manufacture, and
Do Not use a gap other then as specified by the manufacture.
