josseaux asked this question on 5/10/2000:

bonjour i am in saudi arabia and i own a 20 feet day cruiser motorised whith a 150 hp mercury black max v6 mod 1984 .because nobody know any thing seriously about mechanic i can not have any answer for theses questions: what kind of spark plug may i use depending if i use it for trolling or hight speed (temperature of spark plug is different in this cas) if you give me a number for ngk,is it possible to give me also in different brand like champion,ac or yamaha because they don't have any table of correspondance. other question: when i start and when i use it for trolling the engine smoke a lot and produce a huge vibration,i use only 2% oil and when i stop trolling to increase speed it need time to run with 6 cylinder.the carburator jets are the basic 0.98.allways during acceleration from zero to full trottle there is a hole during 1 to 2 second and after it run very well. im sorry for my poor english and i hope somebody will understand my problems in advance i thank you a lot.

cetaylor gave this response on 5/10/2000:

It sounds like you might benefit from the "Split Fire" plug, marketed here in the U.S. I don't have a chart with me here at work, but I will check into it and get back to you tomorrow.

cetaylor gave this follow-up answer on 5/11/2000:

Splitfire number SF263D, NGK BU8H (6431), Champion 885. Check Overtons at www.overtons.com for Splitfire Plugs $3.99 ea.

The average rating for this answer is 4.

josseaux rated this answer a 4.