Correct Spark Plugs for Merc 470

[SSV177]

Had this Merc 470 beast for 27 years in my Glastron SSV177 and been threw the many problems that I see on the forums about this engine.Just winterized the boat for the season and was going to change out the plugs. Last mechanic that changed them said I had the wrong ones in the engine which according to my Merc owners manual is either the Champion RBL9Y or the AC R42TS.He installed Champion RV9YC. Upon searching the various plug companies I found I could use the Champion RV12YC or RV9YC,the NGK BPR6FS or some from AC that I forgot the numbers. Anyone know of why the changes or the differances in the plugs and maybe advise which ones they have had the best success with. Thank you and safe boating!

 

[ErieRon]

Re: Correct Spark Plugs for Merc 470

All of those numbers are correct cross references to the original. I use the NGK BPR6FS. As far as I know the originals simply aren't made any more. I've used the Champion before, but settled on the NJK just because of their reputation. Never had any problems.

 

[Don S]

Re: Correct Spark Plugs for Merc 470

What year is it, and what model number? 470 was used in the early years, but they used a lot of different numbers also.
A SN for the engine would also help.
Things may have changed over the years since the owners manual was printed.

 

[SSV177]

Re: Correct Spark Plugs for Merc 470

The boat/motor is of 1982 vintage with an engine serial number of # 6037775.
I think I will try the NGK plugs this time as I have had good luck with them in other motors that I have used them in. Thanks for your kind help.