[99 Mariah 258]

Hello everybody,
Was planning a tune-up and there is a thousand different part numbers for the wire set.Does anyone know a part number for a set for my 1999 Mercruiser 7.4 Mpi & if I have a Delco or thunderbolt ignition.....Thanks

Also.... I purchased some NGK "Marine" spark plugs but they don't say marine and look pretty generic...Thinking of returning them .Anybody run these?

[ShabahZ280]

Not sure of the spark plug wire part numbers, but I do run NGK plugs, and have for years. There's really no indication on them that they're "Marine". Just run a double-check on their website using the "parts finder" and look up your engine info. If the part numbers match, then you're good to go!

[Hudson River Steve]

I believe the correct Mercury Quick Silver ignition wire kit is part number 84-816608Q68. While you are at it you may want to change the distributor cap 808483T3 and rotor 8M6001253 as well. Look closely at your coil mounted on the rear of the intake, they have a tendency for the steel laminations to rust and swell over time. If it looks bad, just change it before it is a problem part number 898253T27.

You didn't mention what part number NGK plugs you bought but I believe the correct part number NGK spark plug for the 7.4L MPI is BPR6EFS. This plug has a zinc coating on the steel shell to help prevent corrosion. You can also use AC MR43LTS, this also has a coating on the steel shell.

Good luck!

[99 Mariah 258]

Originally Posted by Hudson River Steve

I believe the correct Mercury Quick Silver ignition wire kit is part number 84-816608Q68. While you are at it you may want to change the distributor cap 808483T3 and rotor 8M6001253 as well. Look closely at your coil mounted on the rear of the intake, they have a tendency for the steel laminations to rust and swell over time. If it looks bad, just change it before it is a problem part number 898253T27.

You didn't mention what part number NGK plugs you bought but I believe the correct part number NGK spark plug for the 7.4L MPI is BPR6EFS. This plug has a zinc coating on the steel shell to help prevent corrosion. You can also use AC MR43LTS, this also has a coating on the steel shell.

Good luck!

Your the Man......Thanks again