Spark Plugs

[Boilers2000]

I have what I have assumed is a 92 4.3LX mercruiser V6. Serial # shows D828755 or might be D626755 (I'll try to attach a pic). I have been using service manual 7 which says it covers serial number B775130 -F000000. The service manual lists Champion RV15YC4, but other sources for the same serial number range list Champion RV9YC for NGK BR6FS. Physically those two spark plugs are different lengths. Am I using the wrong service manual? I know I could go pull a spark plug, but havent had a chance to get to storage and want to make sure I have everything to get ready for summer.. TIA for the help

 

[Boilers2000]

Also have this picture from the engine cover. Clearly a D826758, so I would have expected service manual 7.

 

[Scott Danforth]

1996 and newer use long plugs (vortec heads)
1995 and older use short plugs (non-vortec heads)

 

[LundAngler1650]

 

[LundAngler1650]

Just screen shots, of what I googled.

 

[Bondo]

Ayuh,..... It's a Chevy motor, 'n I only use AC Delco's in Chevy motors,......

The MR43T for motors up to '95, 'n the MR43TLS in the '96, 'n later motors,....

The AC Delco marine spark plugs are Not Plated, they're an alloy body, 'n don't rust into the heads,.....
That's where the "M" in the part number comes from,.....

 

[Boilers2000]

1996 and newer use long plugs (vortec heads)
1995 and older use short plugs (non-vortec heads)

I compared the two different plugs the threaded part/spark part appear to be se same length and thread size, the ceramic and end is where one is slightly longer than the other. Is it fair to assume that if the reach and diameter are the same then the spark plugs are comparable and the overall length is cosmetic? Also gap of 0.035 inches is the correct gap. The Champion catalog at west marine listed 0.040 inches.

 

[Boilers2000]

Thanks I'll probably go grab some of the AC delcos as well.

 

[Boilers2000]

The head size on that spark plug is 13/16th vs 5/8 of the other ones.

 

[Boilers2000]

Misread spec chart, spark plug hex size is 5/8", but reach is 12.3mm and and on the champion I believe it's 11.2mm. Is reach the part the goes into the engine block? More curious about that 1 mm difference.

 

[Boilers2000]

AC Delcos are what are in now and what will be replaced.

 

[tank1949]

I have what I have assumed is a 92 4.3LX mercruiser V6. Serial # shows D828755 or might be D626755 (I'll try to attach a pic). I have been using service manual 7 which says it covers serial number B775130 -F000000. The service manual lists Champion RV15YC4, but other sources for the same serial number range list Champion RV9YC for NGK BR6FS. Physically those two spark plugs are different lengths. Am I using the wrong service manual? I know I could go pull a spark plug, but havent had a chance to get to storage and want to make sure I have everything to get ready for summer.. TIA for the helpView attachment 338816

How many past owners and did any change heads, etc???

 

[Boilers2000]

How many past owners and did any change heads, etc???

Best I can tell I previous owner, searay name plate matched title so assuming 1. Don't know if heads changed, but I'll replace with what's currently being used, which matches service manual.

 

[Scott Danforth]

if the intake manifold has 12 bolts, its non-vortec heads. if the intake manifold has 8 bolts, its vortec heads

 

[QBhoy]

Br6’s all the way. I’d be sure.

 

[Boilers2000]

Bought new AC Delcos. Compared to the NGKs the reach appears the same, but AC Delco overall body is longer. Will probably replace like for like.