How are you supposed to…

[Capw]

Index spark plugs when 3 face the exact wrong direction? I’ve moved them around but 3 will not cooperate. It’s not as if there’s an adjustment.
2B362086 17’ ProXs 250 2 stroke

[Fishing Addict]

I could be very incorrect but, I don't believe plugs need to be indexed on a Merc.

[Rick H]

Buy more plugs

[bass.man65]

Why are you trying to index them? They do not need to be indexed. Torque to 20lbs and your done.

[Bryanmc57]

Indexing plugs is an evinrude thing....

[Capw]

Thank you!

[JOE54]

yep ^^^^^

[EuropeanAM]

"It's a RUDE Thing". That's why it's not working on your Merc.

[DewRonInc]

Lol, Don, it don't hurt to index, u will need about three sets to get close, seems to help mine a bit

[EuropeanAM]

We actually did do a considerable amount of testing with that. Biggest thing is to make sure the arm doesn't face the Direct Injector (45 degrees either side). Any other angle was fine.

The latest of the 200 ProXS Optimax engines were especially unhappy if you got that arm into the plume area (since the pistons and DI's don't match).

[lpugh]

We actually did do a considerable amount of testing with that. Biggest thing is to make sure the arm doesn't face the Direct Injector (45 degrees either side). Any other angle was fine.

The latest of the 200 ProXS Optimax engines were especially unhappy if you got that arm into the plume area (since the pistons and DI's don't match).

.
when you say facing, I take that to mean where the ground electrode is attached to the plug, since it would shroud the spark, deflecting fuel molecules away. Think I may have been seeing signs of this on the deposits of the porcelain. Have noticed a few motors that would have an occasional skip at idle in them like a misfire would cause, such a minor thing that I have not pursued in depth as to the cause.
I have 200 non xs here right now that does this.
I might start a new post and peruse for educational purposes.

[EuropeanAM]

I would actually draw a line on the porcelain to indicate where the arm attached to the plug base. The line would preferably not point toward the direct injector (any other orientation ok).

What I have found is that if the spark plug is consistently torqued with a TORQUE WRENCH to 20 lbs/ft, I very, VERY seldom even give this a moment of concern. Even that pesky 200 ProXS (later group) seemed to idle decent when the plugs are torqued with a wrench.

I believe the interference was more related to the returning vapor and flame propagation AFTER the atomized fuel hit the "dish target" on the crown of the piston. This would also explain why that 200 ProXS group is SO finicky: It breaks most of the Optimax "cardinal rules" by intermixing standard Optimax and ProXS-line components in the same engine.