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-   -   How does this spark plug look? (http://www.hotrodders.com/forum/how-does-spark-plug-look-181577.html)

kyle86 07-24-2010 01:22 PM

Help reading this spark plug?
 
After 2 WOT runs. The silver line on the insulator is where I cut too shalow the first time. The black smudges is where I touched it with my greasy hands :P
thanks

http://i701.photobucket.com/albums/w...ber2/plug1.jpg

Argess 07-24-2010 02:30 PM

Last time I had a plug like that, the timing was way too far advanced and I was getting detonation.

On the other hand, it could be very, very lean.

From what I understand, a water leak into the combustion chamber can also do that, but I think too far advanced timing is the most likely cause.

kyle86 07-24-2010 03:10 PM

Cause of what? I cut that plug open with a hack saw. I thought it looked on the rich side since the fuel ring is so high up.

Argess 07-24-2010 03:17 PM

The cause of it being pure white. Advanced timing can make an old crusty plug look bone white again.

I didn't see that you only did two runs with it though. Maybe just ignore me.

Dajerseyrat 07-24-2010 03:24 PM

From my experience it looks a tad lean to me, I like a hint of tan/sandy color to mine to be safe...Was the plug removed right as you finished the WOT runs? Or did you drive around cruising for a bit afterwards?

I always check my plugs at the track right as I enter the return road, I pull over and pull one asap, thats the most accurate way to read em.

What kind of carb?What Jets?what weather conditions? also how high compression on your motor?

On a side note, Why did you cut them opened to read em? You dont have to do that..

kyle86 07-24-2010 03:31 PM

Quote:

Originally Posted by Dajerseyrat
From my experience it looks a tad lean to me, I like a hint of tan/sandy color to mine to be safe...Was the plug removed right as you finished the WOT runs? Or did you drive around cruising for a bit afterwards?

I always check my plugs at the track right as I enter the return road, I pull over and pull one asap, thats the most accurate way to read em.

What kind of carb?What Jets?what weather conditions? also how high compression on your motor?

On a side note, Why did you cut them opened to read em? You dont have to do that..

Ran down the strip, went back to the pits and then pulled some out.

Holley carb 750 vs, 76/80 jets, humid 86 degrees, 10:1 compression or slightly under.

I cut them open so I could see the fuel ring down in there. I tried with a magnifyling glass and flashlight with no luck. I don't have an ottoscope.

Dajerseyrat 07-24-2010 03:37 PM

Quote:

Originally Posted by kyle86
Ran down the strip, went back to the pits and then pulled some out.

Holley carb 750 vs, 76/80 jets, humid 86 degrees, 10:1 compression or slightly under.

I cut them open so I could see the fuel ring down in there. I tried with a magnifyling glass and flashlight with no luck. I don't have an ottoscope.

Same comp as mine, same size carb,same jetting as mine..In 78 to 80 degree weather My plugs had a bit more tanish to them..I would make the secondaries .82 and do another pass if you pick up MPH your going in the right direction, pull it and see..Lean is mean, but Im more conservative, cause if it dropps to the low 70's youll run even leaner..

Try the .82's should look a slight bit more tan..(thats how I like it anyhow)If it dont slow you down, run with the slightly richer jetting, to be on the safe side.

Fronts, leave em alone..Do some street cruising with no WOT runs, and then pull the plug after driving for 20 minutes..Dont let it idle to much, just drive 2500-3500 rpms..

Should look nice and tan.

SDLuck 07-24-2010 08:48 PM

Reading spark plugs is like a science.I spent a lot of time on a dyno many years ago.Either go to a dyno or change jets and read mph.Anything else is asking for trouble.On a 1600 vw we dynoed the operator killed the motor on a load and we checked the plugs, they looked lean to all of us .The dyno operator was quiet,so I asked him. He said he couldn't read spark plugs but by the bsfc numbers it was rich so we leaned it out and over the process picked up 12 hp.Plugs always looked lean

4 Jaw Chuck 07-25-2010 12:07 AM

That plug looks slightly rich to me, not bad though and might be OK for power if the temps were high that day and you want a jetting that works for colder weather (under 60F).

I don't use rings on the insulator for checking jetting, the fuel today doesn't color them well like they did in the old days. Use the ground electrode instead, the tip should be blue and the carbon on it should be gone almost to the shell. Using that criteria that plug looks rich to me, unless your running race fuel of course.

Drop two sizes and post a pic again.

ericnova72 07-25-2010 02:16 AM

Looks pretty decent to me, heat range looks right, we prefer the heat line on the strap to be right at the bend, so you look fine to me. Like has been said, jet up and keep watching the mph.

If you keep jetting up and it goes faster, and you go more than 4 steps up in the front(or rear), .. and you street drive the car you can trade some of that fuel over to the power valve channel restrictions(PVCR), enlarge them and go back to leaner main jetting for economy. Get the best of both worlds that way.

kyle86 07-25-2010 02:31 AM

Quote:

Originally Posted by 4 Jaw Chuck
That plug looks slightly rich to me, not bad though and might be OK for power if the temps were high that day and you want a jetting that works for colder weather (under 60F).

I don't use rings on the insulator for checking jetting, the fuel today doesn't color them well like they did in the old days. Use the ground electrode instead, the tip should be blue and the carbon on it should be gone almost to the shell. Using that criteria that plug looks rich to me, unless your running race fuel of course.

Drop two sizes and post a pic again.

Thanks for the info! I will post an update after I drop a couple rear jet sizes. I have to order them from summit since I'm missing 78s.

Just curious, when you're looking on the ground strap, how do you defrentiate between fuel and the heat range? I know I can run a 1 step hotter plug and it will take the color past the bend. I'm a newb at spark pug reading so I'm trying to get the technique down. Thanks!

kyle86 07-25-2010 02:36 AM

Quote:

Originally Posted by ericnova72
Looks pretty decent to me, heat range looks right, we prefer the heat line on the strap to be right at the bend, so you look fine to me. Like has been said, jet up and keep watching the mph.

If you keep jetting up and it goes faster, and you go more than 4 steps up in the front(or rear), .. and you street drive the car you can trade some of that fuel over to the power valve channel restrictions(PVCR), enlarge them and go back to leaner main jetting for economy. Get the best of both worlds that way.

Sweet, thanks! I guess I should try going up some, and down some and see how it responds.

Yea I've heard about drilling out the PCVRs. That's one thing I eventually want to try when I get the WOT tune down. I'm kinda nervous since it's irreversible, but metering blocks are cheap anyways.

ericnova72 07-25-2010 03:58 AM

Drill and tap the PVCR's to 6-32 thread so it will accept screw-in restrictions. You can either get them predrilled, or buy blanks and drill your own.

Dajerseyrat 07-25-2010 09:41 AM

See how the difference in opinions on the color of the plug vary...I would invest in a nice Widband O2 sensor like a Innovate brand, or AEM...These will allow you to bring a laptop to the track and log the pass in real time, then go back and look at the data of the A/F..

I personally like my pump gas N/A cars in the 12.5-13.0 range for power and safety..

kyle86 07-25-2010 11:47 AM

Quote:

Originally Posted by ericnova72
Drill and tap the PVCR's to 6-32 thread so it will accept screw-in restrictions. You can either get them predrilled, or buy blanks and drill your own.

Is there a link you can post of these? I am very interested in them.


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