Anyone index their plugs? Notice any diff?

[Todd157k]

Being boat motors run at higher rpms than most cars, I was just wondering if anyone indexes their plugs and if so, notice any difference....?

 

[Brewman61]

Re: Anyone index their plugs? Notice any diff?

What is indexing, never heard of it. Just curious.

 

[dubs283]

Re: Anyone index their plugs? Notice any diff?

indexing plugs means facing the ground tabs in a certain direction for optimum fuel/air burn in the combustion chamber

the only engines i have heard of really needing this are DFI outboard engines, specifically Evinrude E-TEC engines. Merc Optimax engines do not require indexing of the plugs

the reason they index the plugs is due to the fuel being injected directly into the combustion chamber. the indexing aids in controling the direction of the burn across the pistion

i have never heard of indexing plugs on sterndrive engines and can't see any reason as to how this would aid in combustion/performance

 

[EddiePetty]

Re: Anyone index their plugs? Notice any diff?

Being boat motors run at higher rpms than most cars, I was just wondering if anyone indexes their plugs and if so, notice any difference....?

....I tried it on my 3.7 without any noticeable gains. I really don't believe our I/O's turn fast enough for indexing to be effective. Now on my former racing engines turning 7K+...the difference was noticeable: especially when we went injected!!

Edit:
Should and engine have leaking valve guides or other oil consumption problems, indexing could be used as a band-aid to reduce fouling until overhaul time......but it's just a crutch.

 

[Bondo]

Re: Anyone index their plugs? Notice any diff?

Ayuh,.... My sparkplug indexin' is done at the factory,...

Wherever Chevy taps the holes to, is where mine are Indexed....

 

[bruceb58]

Re: Anyone index their plugs? Notice any diff?

Indexing is a complete waste of time.

 

[Aloysius]

Re: Anyone index their plugs? Notice any diff?

Indexing is only applicable to certain conditions..one mentioned above, the other is physical clearance of the ground electrode and some part of the piston, only found on extreme racing engines.

 

[a70eliminator]

Re: Anyone index their plugs? Notice any diff?

For your average run of the mill boat I agree, no noticable gain, but paying attention to detail never hurts.

 

[Borchik]

Re: Anyone index their plugs? Notice any diff?

Indexing on sterndrives is very rare, high power direct injection efi setups use this, big race boats and stuff where it is a necessity. Certain DI outboards also does make a big difference. But for most stuff on the water there is no need.\\

 

[Todd157k]

Re: Anyone index their plugs? Notice any diff?

Interesting. I didn't really ask "how" or "why". I know how, and why, and the benefits/theory.
I was curious because of the guys with large motors/drives. I know there's a lot of jet boat guys that index.. and yes, even on carb'd / blown motors.