Another sparkplug question

[bassboy]

I have a 94 2.5 200 XRi and my service manual calls to run NGK BU8H surface gap plugs, when troubleshooting ignition problems it also suggests BUZ8H, less RFI to disturb digital ECU. The motor has an ECU that has a digital part number but has an external TPI adjustment. I would like to try a gapped plug and wanted your opinion. I was thinking of a BR8HS. Because this is a basser I do a lot of idling and get a lot carbon buildup on the piston tops, impossible to read. I do NOT want to burn a hole in any of my pistons! What do you guys suggest? I have been running the BUZ8H for sometime now but it isn't long before they ohm out as open, resisters shot. If you all think it's best I will go back to the BU8H. Thanks guys!

[sho305]

Whenever we read plug/pistons on any boat motor (OB or I/O) we would run at that speed/rpm in question for a while under load, then slow down and shut down as fast as possible and check them. I assumed that was the best way to do it? The idle never shows you a read as far as I know, and it will not idle right if the idle mix is off much. I can never read my inline surface plugs, just pistons. They work well though.

If you mean carbon problems, I never idle that much;) but most here recommend using the merc additive to reduce carbon for fear of sticking rings. I think someone else makes one too. I need to get some, I have never used it but then I don't get that many hours on my motors anyway.

[Markus]

The BR8HS will not burn a hole in your piston, if that is what you are asking.

If you are asking about how to read a spark plug to make sure your air/fuel mixture is not too lean, read the excellent article by Gordon Jennings that you can find through my links page (see below this post)

[bassboy]

Thanks you guys, I was just looking for a plug that gaps to help make reading easier. I know that with all the idling I have to do for fishing that it will be hard anyway, but surface gap plugs make it almost impossible. I was also concerned about spark intensity with surface gaps on pistons with too much carbon, maybe that's not an issue but I thought it would be something to try...

[Markus]

When reading plugs, you will only get useful information when you make a plug chop with fresh plugs at the RPM where the engine is at its leanest.