NGK YR5 or BR6FS for 140hp 1980

[Alumarine]

Just picked up a 1980 Sylvan with a 140hp mercruiser serial no. 566xxxx.
I thought the plugs for it were BR6FS but the NGK site lists the YR5 as the plug.
Is this correct? If so, what is the difference?
I've sent an email to NGK but haven't heard back.
thanks

 

[ziggy]

i'd go with the BR6FS. that's what s/m #3 calls for specifically on pp 1B8. funny, actually what s/m #3 pp 1b8 calls for is
AC-MR43T or
Champion RV8C or
autolite 144 or
NKG-BR6FS i would assume it's a typo.

 

[Alumarine]

Thanks for the info. I picked up some BR6FS's.

 

[Fun Times]

BR6FS but the NGK site lists the YR5 as the plug. what is the difference?

With the NGK's, the lower the number is, the hotter the plug will be.....While AC-Delco is, the higher the number is, the hotter the plug will be.

I've seen a few times now the NGK site lists different plug numbers than what Merc says to use.

Your engine calls for either NGK BR6FS or AC-MR-43T (< same heat range) while AC Delco 44T cross references over to NGK YR5. < Higher heat range.

http://ngksparkplugs.com/pdf/DYK_HeatRanges.pdf

http://www.google.com/url?sa=t&rct=...1c0TtlC04w47CPmL1vBFeoA&bvm=bv.76802529,d.cGE

 

[Alumarine]

With the NGK's, the lower the number is, the hotter the plug will be.....While AC-Delco is, the higher the number is, the hotter the plug will be.

I've seen a few times now the NGK site lists different plug numbers than what Merc says to use.

Your engine calls for either NGK BR6FS or AC-MR-43T (< same heat range) while AC Delco 44T cross references over to NGK YR5. < Higher heat range.

http://ngksparkplugs.com/pdf/DYK_HeatRanges.pdf

http://www.google.com/url?sa=t&rct=...1c0TtlC04w47CPmL1vBFeoA&bvm=bv.76802529,d.cGE

Thanks for that explanation. That makes me like the BR6FS's even more.

 

[Alumarine]

Here's an update. I got a reply from NGK.

"Hello,

For that application part number BR6FS is the correct spark plug. The current part finder can be difficult at times and we are in the process of releasing a new website with an improved part finder.

Regards, "

 

[thumpar]

Merc uses AC so that is what I use. I use NGK in foreign engines.

 

[airshot]

I had used the AC plugs for a couple years but had some minor fouling problems. Switched to the NGK BR6 plugs and have not had an issue since. Based on that fact I would recommend the NGK plugs

 

[achris]

In Australia, AC plugs are hard to find. I use the NKG plugs without any problems. I don't think that you would have any problems with any brand of plug, with the exception of champion....

Chris....

 

[thumpar]

In Australia, AC plugs are hard to find. I use the NKG plugs without any problems. I don't think that you would have any problems with any brand of plug, with the exception of champion....

Chris....

+1 I can get the AC within a mile or so from my house. If I couldn't get them easily I would go with NGK.