Spark Plugs standard Vs Platinum
 

So I am getting ready to perform the spring maintenance on my boat which has a fresh 509 in it with about 8hrs from last season. I have always run MR43T's in all my marine engines but I read an old thread about people running Rapid Fire #1 which is the platinum version of the MR43T's. My boat is on a lake where maybe it sees 10-14hrs of run time the entire season and almost no long durations of WOT, it spends most of those hours between 3 & 3,800RPM's With that said is it smart to switch to a Platinum or stick with the trusty Standard core plug?

The extra money for platinum's aint worth it to me considering i changed plugs yearly anyway! Just verify the plugs are looking good as far a the color goes burning fuel...you might consider going up or down in heat range....if need be but i would just stick to the basic stuff since you wont see any perf gains with just plugs lone :)

This is what I was thinking too just wanted your opinion.

You can run a lot of hours on a platinum or iridium plug, but it just irks me to pay $10-$12 per plug. Pulling the mr43’s give me a chance at inspection and compression test just to keep tabs.

I ran Rapid Fires #1's a long time ago. The only difference from them and MR43's was that they did not foul out at idle on my engine.

I just went with the MR43T's again they never gave me an issue so why mess with something that works.

The benefit of Platinum or Iridium plugs is reduced center electrode wear. The spark wants to jump at a sharp point. Rounded standard electrodes tend to round off and not be as effective at the spec'd plug gap.

Can often run wider spark gaps.

I've bead blasted my Iridium plugs to get the carbon cleaned off them...them they're good as new. The iridium tip is something like 4500°f laser welded on.

Nothing wrong with running what works for you. Just being able to change the plugs with engine mounted is a bonus.

Slight contortionist task in my boat but I'm a little person so I can cram back there to change them. Again my boat maybe sees 12-16 hours of run time a season and I think I'm estimating high.

Race prepped engines will often have the centrctrode filed to a narrower point. Only needed for a short time and creates t platinum and iridium effect

I wish I could change my plugs...even with a 3/8 batt ratchet won't get all of them.

Big gaps are more of a concern (issue) than anything else ignition wise.
Standard plugs / wires / caps / rotors / coils lead a very long time on marine engines with normal .035” gaps. Even the individual coil engines.

Is .o35 the typical gap on these big blocks? Now that I'm on an MSD box with a matching coil & distributer would opening the gap another .005 to .010 worth anything besides possible misfire? I know in the boosted world when playing with my turbo cars im down a .022-.024 to avoid blow out but on an NA motor is a bigger gap better for a larger spark or is that BS?

.035 is what i fond most often but i do remember back in the early 90's right out of high school i had a buddy that had a 3500 silverado with a 454....it had an HEI dist and i distinctly remember it calling for a gap of .045 for that truck.....so id say it just depends. You can get away with a higher gap with a hotter ign system.....and ive even seen some old timer open the gap on some SBC's that ran crappy and it smoothed out the idle...not sure if the bigger gap help a rich condition or what but it did work.

Marketing says bigger gap better.:rolleyes
I say, gap to .035”-.040” and worry about other things. :)

Bigger gaps just make ignition issues needing parts replacement happen earlier.

Some older hei’s used ,060” gap. Lol.
Better for emmissions back then, but boy did they eat parts. Cap center buttons, modules, etc.

You know my way back fix on all the gm crab cap issues on the ‘96+ vortecs with cap misfires and burn thru ? .035-.040” plug gaps. :) Fir years i’d watch others fight the cap issue. Lololol. Painful !!!!

As i’ve posted a bunch, reducing plug gap to .035” on the 496’s (even with their individual coil near plug arrangement) will surely reduce ignition wire and coil issues they seem to have. I’ll put money on it. :)

Point taken .035 Gap it is for me!