Performance Spark Plugs

[egleissner]

According to the previous owner of my 1997 PRE2150WT, the spark plugs and wires have never been changed. I was going to do this in the spring and I was debating if the high performance spark plugs like iridium or platinum are really any better than the cheaper standard. My engine is a 1997 Marine Power with a Chevy/GM VORTEC 350 base. Anyone have any good suggestions?

[dogbert]

My dealer recommended changing the plugs every 400 hours and, when doing so, replace the plug wires at the same time. I'm not sure you'd get any better performance from platinum plugs. Plugs are cheap, plug wires, not so much.

[Jason B]

I've used both cheapies and expensive plugs in my truck and I could not tell any difference in the mileage or performance. There may be an environmental issue perhaps if they truly burn better as promised and burn cleaner. I never did a scientific test about the reduction of pollutants or any such nonsense so you're on your own with that. My logic behind buying the expensive ones was that I had the money--why not? Not sure if I'd do it again now that I'm a little tighter with what $ I waste.

[Guest]

Platinum plugs burn a tad hotter but the biggest advantage of platinum vs regular plugs is that platinum plugs will last much longer.

[dogbert]

Trucks are different from boats. Boats run at much higher RPMS and this leads to more wear and tear on the plugs and wires. It's also my understanding that your engine's electronics need to be compatible with platinum plugs. My Merc 350 MPI is not. I actually asked my dealer's service manager that question a while back and he said not to do it.

[TRD]

Trucks are different from boats. Boats run at much higher RPMS and this leads to more wear and tear on the plugs and wires. It's also my understanding that your engine's electronics need to be compatible with platinum plugs. My Merc 350 MPI is not. I actually asked my dealer's service manager that question a while back and he said not to do it.

Dogbert,
What plugs and wires do you run or recommend? I am planning on changing mine this year (or this wkend).

[dogbert]

I got mine from the dealer, so I don't actually know. Maybe lee knows?

The other issue with the Merc 350 is that you need to replace your distributor cap as often as your impeller, maybe even more often. Not sure what's happening there, but they don't seem to last long and boy, things go to hell pretty quickly when it needs replacing.

[TRD]

I got mine from the dealer, so I don't actually know. Maybe lee knows?

The other issue with the Merc 350 is that you need to replace your distributor cap as often as your impeller, maybe even more often. Not sure what's happening there, but they don't seem to last long and boy, things go to hell pretty quickly when it needs replacing.

Thanks, didn't know about that.

[TeamAllen]

I have always used NGK as my spark plug of choice. Nothing fancy just a good solid performer.

My understanding of the plugs using other metals are for longer duration. (As 1Lab_Trainer said) There might be some added benefit to the iridium plugs as there is less resistance which puts less of a load on your ignition system. But at the cost of those iridium plugs, I would rather replace my NGk more often and get a good look at cylinder conditions.

[Razzman]

The biggest benefit of the more expensive "performance" plugs is that they can produce a hotter spark and in some cases last a bit longer. Unless your running high octane fuels (not recommended) you'll see absolutely no benefit. The longer lasting plug will cost $5 plus and the average plug $2, not worth it. Any major brand plug is good and will last for the duration, i've used them all and for the money i prefer Autolite but that's just my pref. Because of the nature of these boats and how they are used it really doesn't matter.

Good quality silicone wires will last a long time, and are pretty much indestructable unless laying right on a manifold. 8mm are better not because of performance but because they promote a hotter spark over the distance which of course is more efficient and hence burns the fuel better. However 8mm wires may not fit into your wire looms and you'd have to enlarge the openings as i did with a drill bit. 7mm will do just fine if you don't want to hassle it. Regadless of which wire set you get make sure to get the made for your motor set, not the one you have to make up. They suck, plain and simple.

Make sure to check your cap and rotor as Dog stated, the best plugs and wires will do no good if they are bad. Make sure you add dilectric grease to all the plug wire ends, not only does it make a better electrical connection but it also helps waterproof the terminations.