WPSLPGExhaust Gas Oxygen (EGO) sensor Information

[Bruce Plecan]

> Great suggestion.   Now can anyone help out with how to read plugs?

Only in general terms, descriptions.  This is again, getting to an art form.
You, just to a large extent, have to do, and pay very close attention to the
details.
It's something that takes practice.
Lots of it.
Also, just because you can "read" the plugs, doesn't totally resolve having
several mistakes covering ecah other up.  You have to experiment with the
tune, for it to be it's best.
You can do things like too cool of thermostat, with too hot of plug, with
too much fuel, and wind up with a resonably good looking plug.
There are certain tuning items that just make sense,  that folks like to
""improve"" upon, without thinking about what they are doing.

>  Specifically I know that you can read a plug for things like WOT mixture,
> ignition advance, heat range and so on.  My current project involves
> playing with ignition advance.

For AC / Autolites, (others vary slightly in some areas)

WOT mixture, should leave the plug slightly darker then bone white, leaning
toward beige.  If white leaning oward black, the you've probably got a real
rich spot (momentarily) in there.
Plug heating wrong (too much timing or heat range), will cook the bounding
agent out from between the porclean, and center electrode.  OR, the side
electrode will get a metallic green or metallic blue hue to it.
Any heavy black flakey deposits to much fuel
Any black glossy deposits, oil
Physical damage to the plug way too hot / lean (assuming no trash ran thru
the motor.
The depth of the fire ring (that off white area) can tell you where you are
timing wise, but that judgement will come with time.

Assuming that I have heat range and mixture
> set properly and non-variable,  I am advancing/retarding the advance for
> maximum power while retaining good driveability for a street machine.

The two run hand in hand, you can't properly tune an engine assuming one or
the other is right.  You have to understand what the engine wants,  YOU CAN'
T tell an engine what you want it to do.  So many people get this
backwards..  You have to, have to, give the engine what it needs.  My own
SBC with AL heads, likes 28-30 total timing.  According to general theory
that is no where near enough, oh well, looks like theory don't mean much
when it doesn't work.

  The
> experts say to watch for rounding of the sharp edges of the center
> electrode,

That's more from age, or actual plug metalergy (?).  The soft metal plugs
like Champion have that rounded edge problem, whereas the Autolites are of a
less erosive metal.  So that's an overgeneralization IMHO

fuel deposits on the sides of the center electrode

Well, ya, that's what's being read.

 as well as
> watch for salt and pepper flecks on the porcelain insulator.

Detonation.  Those flecks are parts of the piston dome leaving the engine.

> My questions are:
> Is a good high speed run ( speed limit + 10-15 mph) on a public road for
10
> miles or so enough to produce any of these results?

To the WELL Trained eye if they have some use on them probably.

> Will fuel deposits form visible enough to read seriously in this amount of
> time?

Again, experience counts.
I can probably detect Manganese in fuel with a new plug after 3 mins of
idling.  Course been looking for it for 15 years.
The stuff is getting really wel laced with detergents, and kinda tricky at
times to see what your seeing.

> How can you distinguish detonation induced flecks on the porcelain from
> fuel deposits or electrode erosion specks?

Detonation are fly turd size.  Fuel splashing deposits are much larger,
electrode erosion specks, that's a new one.  You can have electrode
tracking, but I seen that once in like 30 years.  You can also have
electrode bleed over, but again so rare to not even be a consideration.

> Ain't any insecurity in saying to learn to walk before you try to run--as
> in learn to read plugs before trying to use a sensor (an EGO or a HEGO)

Truer words, yada yada
Grumpy

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