2000 Carver 406 7.4 MPI Spark Plugs

[crquisto]

I can't see placards on my engines and couldn't get an answer from my books, so I'll just ask here: Does anyone know what spark plugs are specified for the Mercruiser 7.4 MPI engines on my 406. They are probably 1999 engines instead of 2000.

[SplashyLady]

1999 huh? The 7.4 engines of this vintage are in a "donut hole" with a generation change right in the middle.

Seloc and Mercury would likely list AC MR43LTS, Champion RV12YC, or NGK BPR6EFS

But check what comes out - some 7.4 engines around 2000 changed to CHAMPION RS12YC or NGK BPR6FS plugs.

The RS12YC and BPR6FS have a reach of .708 - RV12YC and NGK BPR6EFS plugs have a reach of .406

Should be a plate on the side of the engine with the plug spec - and you can always put in what came out - assuming she was running... I am an NGK fan myself, but some folks love Champion.

[crquisto]

Thanks Splashy Lady. I'll check all you suggested. Thought the placard would be on the top cover or front - didn't look too closely at the sides of the engines. I'll try again and, failing that, will just go with what was there since they've been running well.