do you use spacers to index your Optimax plugs?

**David** · 03-25-2023, 08:24 PM

I have been just buying a lot of plugs and using the ones that index correctly in each hole. It's time consuming.

Gapping and Indexing - NGK Spark Plugs

Spark Plug Indexing Washers - Free Shipping on Orders Over $99 at Summit Racing

How common is it to use indexing washers?

**25two.stroke** · 03-25-2023, 09:36 PM

I never index optimax plugs and noone at Mercury has ever told me to except on DSI motors which I never see.
Never had a fouling issue unless something else was wrong with the engine.

Etecs I index and I just buy hella plugs.

Note added:
I don't work/build high hp optimax motors. Nothing over 250 hp. On a 300xs or any modified xs making big HP then it might be worth it, but on the typical off-the-shelf optimax I'd say its pointless.

**David** · 03-26-2023, 07:33 PM

It's interesting as we have both the 200XS ROS and a 150 HO Etec that need to have the plugs indexed. The Opti plugs get a lot more oil covered, despite far less idling and a lot more high rpm use.

The Etec plugs are much easier to get at. Evinrude says to change every 3 years - although they still look good.

A related question about the plugs - is it possible to clean the oil off a used plug? It's not as if the electrodes seem to wear.

**Jim Speros** · 03-26-2023, 07:53 PM

I'm likely to get some push back but, I think indexing plugs is a sign of a design short coming.

**David** · 03-27-2023, 09:13 AM

Indexing might be a design shortcoming, but it's recommended for both the Etec and Optimax direct injected engines, so I am stuck with it. It's also required on some (all?) Mercedes Benz direct injected engines, but I can avoid buying one of those.

**hellbents-10** · 03-27-2023, 11:41 AM

I find that the washer thickness needed to get them where you want is less then ideal.

**David** · 03-27-2023, 12:19 PM

Good, someone uses the washers. I hope less the ideal means trying fewer plugs per hole

**Chaz** · 03-27-2023, 11:23 PM

I gotz some of them Opti-pop heads in the recycle pile out back. Never looked at them really close, but I believe the plug is tucked up in a small pocket at an angle. Then they put a cup (like a diesel) in the piston to slow the air down. I rekkon they have better luck lighin the lean charge easier with the gap facin down towards the cup.

For the rest of us, The gap faces towards the exhaust (valve) port. It might not make any more power on certain applications, but it will allow all the plugs to look (from the perspective of , squish, swirl, fuel wash, etc.) the same while your "arriving" @ a tune-up ..

**rgsauger** · 03-27-2023, 11:36 PM

Well howdy, Chaz. You’re back!

**TraceF3** · 03-28-2023, 05:54 AM

Originally Posted by David

Indexing might be a design shortcoming, but it's recommended for both the Etec and Optimax direct injected engines, so I am stuck with it. It's also required on some (all?) Mercedes Benz direct injected engines, but I can avoid buying one of those.

Where is it recommended? Is there a publication?

**David** · 03-28-2023, 08:01 AM

Originally Posted by TraceF3

Where is it recommended? Is there a publication?

I may have over generalized. It is recommended for the 200XS ROS. I don't know about the other Optimax engines.

It is recommended for my Etec as well, but the Etec plugs are a breeze to get at compared to my 200XS ROS.