Carver Owners Forum

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.

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 :-O - 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.

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.