Spark plug reading

[747mopar]

Just curious, growing up racing motorcross you always checked the tang of the plug for an indication (coffee with cream was the goal) but I've noticed allot of the plugs I pull out of these newer cars are really lean looking. What do you guys look for on your old Mopars? I've been tuning my BB and have went from 78 to 88 mains with huge gains in power but it's still looking pretty lean judging by the tang but the base of the plug is finally getting black. I would think going up that much should be showing something but they are still light grey close to white. Already checked for vacuum leaks, timing and stays below 180 even at idle not moving. I just thought I'd ask because I'm going to keep going on the mains until it either slows it down or the tang starts showing some brown. Thanks guys.

 

[IQ52]

With unleaded gas and new plugs the porcelain should be white, and at the bottom of the porcelain where it is glued to the steel base there should be a grey ring about 1/16" wide. You sure can't hurt it by going richer until it slows down.

 

[747mopar]

With unleaded gas and new plugs the porcelain should be white, and at the bottom of the porcelain where it is glued to the steel base there should be a grey ring about 1/16" wide. You sure can't hurt it by going richer until it slows down.

So you don't even look at the metal parts just down in the hole at the porcelain? I'll have to pull one back out and check. Thanks

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Another question, Once I'm happy with the primaries what's the best method of determining the jet size for the vacuum secondary's? I would think that would become really hard to determine by reading the plugs unless you just run it WOT and then pull the plug? Is it just based on performance alone? Sorry for all the questions but the help has led to a huge improvement already and can't wait to see what else it may have but honestly I'm quite pleased as is.

 

[Moparsmitty]

That's what we used to do at the track. After a full run we'd shut off in the traps and coast to the return road, pull off and check a plug. I was always looking for a light brown kind of a hot chocolate color. With today's fuels the plugs tend to look like you are running lean. As long as the plug doesn't look glazed or carbon fouled you are probably close. Plug reading takes a little experience but the best thing you can do to learn is by looking at the plugs on a car that is tuned and running really well to get an idea of what they are supposed to look like.

 

[747mopar]

That's what we used to do at the track. After a full run we'd shut off in the traps and coast to the return road, pull off and check a plug. I was always looking for a light brown kind of a hot chocolate color. With today's fuels the plugs tend to look like you are running lean. As long as the plug doesn't look glazed or carbon fouled you are probably close. Plug reading takes a little experience but the best thing you can do to learn is by looking at the plugs on a car that is tuned and running really well to get an idea of what they are supposed to look like.

Alright, who's going to post a pic????????????? Next time I get to tinker with it I'll post a pic of what they look like. See I learned something very important (this new crap gas reads different). Thanks again

 

[cdr]

Get a wideband tuning gauge. my 2 pennies

 

[Meep-Meep]

The new gas doesn't color the plugs like the stuff back in the day so I'm not sure that's a great indicator. X2 on the O2 gauge!

 

[451Mopar]

I got one of these wideband O2 gauges:

http://www.summitracing.com/parts/inn-3844

 

[747mopar]

Get a wideband tuning gauge. my 2 pennies

Already thinking about it, it will have to wait but I believe it will get one in the future.

 

[miller]

Great info! Never thought about plug reading on the crummy gas these days.

 

[Zancat]

I got one of these wideband O2 gauges:

http://www.summitracing.com/parts/inn-3844

Where's the best place to weld the bung in w/ cast iron manifolds?

Thanks,

Zancat

 

[451Mopar]

Where's the best place to weld the bung in w/ cast iron manifolds?

Thanks,

Zancat

The wideband sensor has its own heater, so it does not need to be close to the exhaust port. The instructions say to mount it "at least 24" from the exhaust port, but before and crossover pipe or cat. Here is a section from the instructions:

2.3 Sensor Placement
Optimum bung placement will vary from application to application, but using
the guideline below will ensure the longest sensor life with the most accurate
readings. Using a bung is the preferred method for mounting the oxygen
sensor in all applications.
Weld the bung at least 24 inches downstream of the exhaust port
outlet (after the collector), or 24 inches after the turbocharger if so
equipped. The bung should be welded before the X or H pipe if so
equipped.
Using a clock as reference, mount the bung between the 9:00
o’clock and 3:00 o’clock position. Welding the bung in the lower
section of the exhaust pipe can result in sensor damage caused by
condensation making contact with the sensor’s internal heating
element.
A 1” bung (provided in the kit) will best protect the sensor. When
fully threaded, the sensor’s tip will sit flush with the exhaust pipe, this
does not adversely effect the readings.

 

[Garys1969RR]

My plug readings have been showing a light tan color, which I thought was good. On Other motors I have seen the light grey or white. I am also using fuel blends to increase octane. The 100 Sunoco tends to color them tan to dark orange. I assume the orange is moving towards rich. Trial and error is the best way for me.

 

[Budnicks]

Alright, who's going to post a pic????????????? Next time I get to tinker with it I'll post a pic of what they look like. See I learned something very important (this new crap gas reads different). Thanks again

This has a good description of how to read plugs, it's from NGK information, but still a good guideline for telling where your at...

Where is says brown with unleaded fuels it will show more tan-ish to a more grey-ish colored... if that makes any sense...

Projected tip sparkplugs will usually read like they are a little leaner/than they actually are, but the rest of the descriptions will work still...

I hope that helps some...

If you can get a plug reading glass that helps to see better down inside & magnifies it some too, but a magnifying lens & a light behind you, so you can see to the bottom well, also will do basically the same thing too...

 

[Daves69]

You say you want pictures...................

http://www.4secondsflat.com/Spark_plug_reading.html

 

[747mopar]

This has a good description of how to read plugs, it's from NGK information, but still a good guideline for telling where your at...

Where is says brown with unleaded fuels it will show more tan-ish to a more grey-ish colored... if that makes any sense...

Projected tip sparkplugs will usually read like they are a little leaner/than they actually are, but the rest of the descriptions will work still...

I hope that helps some...

If you can get a plug reading glass that helps to see better down inside & magnifies it some too, but a magnifying lens & a light behind you, so you can see to the bottom well, also will do basically the same thing too...

Thanks allot Bud, that is some really cool info especially coming from my 1st choice in plug brand. I'll have to compare my plug and see how it adds up for me because I was wondering how to tell if I needed different plugs "now I know". Very cool, thanks

 

[68GTX440]

This might help for a visual. I have had this for a while. I can't find my other ones. (must have lost on a hd crash)

View attachment 192549

 

[747mopar]

You say you want pictures...................

http://www.4secondsflat.com/Spark_plug_reading.html

Thanks, really don't understand why they would be trying to illustrate plug reading with a plug fouled up with oil??? For crying out loud at least use a decent plug.

 

[Daves69]

Thanks, really don't understand why they would be trying to illustrate plug reading with a plug fouled up with oil??? For crying out loud at least use a decent plug.

They want you to spend 10 on the book is my guess.