Indexing Spark Plugs

[Virg464]

Think I'll go ahead and put this idea in the "I don"t need to do it" file. Thanks to everyone for the inputs.

 

[mopar 3 B]

NOT saying you aren't absolutely right. That's basically what I said too. But now I'm wondering if it would make a difference on a heavily nitroused motor, considering that they don't like extended tip plugs?

Heavily nitroused motors don't like spark plugs period. So other than clearance what would be the point?

 

[66Satellite47]

Virg464, I'm sure you are making the right choice. BTW my testing in the '80's was with 906 & 915 heads, 12.4 CR and various plugs, Champion, Autolite, NGK.
Again, no difference at the track.

 

[Endangered Species]

NOT saying you aren't absolutely right. That's basically what I said too. But now I'm wondering if it would make a difference on a heavily nitroused motor, considering that they don't like extended tip plugs?

Could be, I don't know much about how Nitrous effects flame travel. I think what you and I were saying is there really is no performance gain by indexing plugs on a NA motor.

 

[Budnicks]

I used to do it in my altered with a high compression dome
301cid Donovan/Mondello heads, Blown injected alky or gas combo
more for plug clearance SBC had really tight clearances
not much room with high domes
there was guys who ran the extra gaskets/shims to get the plug/electrode out of the way
I went to different style Autolite racing plugs with a shallow ground strap
hardly protruded out at all, I didn't have to do the indexing anymore
didn't make much if any difference on the gas combo either, not on the time slips

I didn't notice any performance changes
it was far more about the altitude & RAD water grains, or track prep
timing & pill or bypasses, than plug indexing/than the angle of the plugs ground straps

same thing on my T/S or Outlaw P/S combo with 3 kits of N2O
plates under the carbs, for launch
spray bar plumbed inside the tunnel-ram, for about 100' out to 330'
port nozzles from that point on, sometimes all 3,
when at a good, low near the sea-level tracks, mineshaft air
6.69 @ 217 best 540cid at Sears Point
4.26 1/8th mile best Scribner Nebraska middle of corn fields
it's far more about the rest of the tune, not being on the ragged edge
then the plug, and electrode angle,
we replaced all of them every pass
I/we rarely had any burned-off electrodes/tips
it far more about the timing burn/bluing on the electrode
showing if timing was correct
or spotting of aluminum down inside/on the porcelain (lean or timing advance death)

it 'may' make a couple of hp, in a dyno room... IMO not really worth it
unless it's on the ragged edge
or need plug clearance, go to a different style plug