Spark plug color
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Spark plug color
So getting ready for Williams gathering and pulled the spark plugs to take a look. The plugs look like they are a lean, but the color tune is blue at both idle and 3000. Any opinions?
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1970 SPL 311-29311
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- keith0alan
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Re: Spark plug color
Are you getting any stumbles at cruise? If not it is fine.
- david premo
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Re: Spark plug color
The plug looks fine, with the unleaded fuel we use now that is the correct color. When we had leaded fuel it would give you a brownish color to the plugs. Looks like a nice mixture, when it is lean the color is extremely white with tiny light black spots cause by the pre-ignition.
Dave
Dave
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Re: Spark plug color
I learn something new every day. I must be tuning mine a little rich.david premo wrote:The plug looks fine, with the unleaded fuel we use now that is the correct color. When we had leaded fuel it would give you a brownish color to the plugs. Looks like a nice mixture, when it is lean the color is extremely white with tiny light black spots cause by the pre-ignition.
Dave
Keith
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Re: Spark plug color
Would be nice to see a pic of a lean plug for comparison.
Linda
Edit: Found a link:
http://www.verrill.com/moto/sellingguid ... rchart.htm
Linda
Edit: Found a link:
http://www.verrill.com/moto/sellingguid ... rchart.htm
Last edited by Linda on Mon Sep 05, 2016 3:53 pm, edited 1 time in total.
Sadly-Linda has passed away 2022. She was the 311's den mother and drove the first Rare-Parts ball joint project. RIP.
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Re: Spark plug color
I had a lumpy idle and found my main jets at different heights. Front two plugs were rich and the rear looked okay to a little lean. I had set them last year. Now something to watch in the future.
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RBMann
mechanic on '69-1600(not mine)
mechanic on '69-1600(not mine)
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Re: Spark plug color
RBMann wrote:I had a lumpy idle and found my main jets at different heights. Front two plugs were rich and the rear looked okay to a little lean. I had set them last year. Now something to watch in the future.
IMG_9118.jpg
Were these plugs ever used? Look like they came right out of the box
67 1600 (Mods only a mother could love)
78 911 SC Targa (Severe Oversteer but still loved)
78 911 SC Targa (Severe Oversteer but still loved)
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Re: Spark plug color
Dave, are you sure about that? I have seen pics from some time ago of piston lands and heads very white from lead. Over the many years since lead went away I have seen lots of tan plugs.david premo wrote:The plug looks fine, with the unleaded fuel we use now that is the correct color. When we had leaded fuel it would give you a brownish color to the plugs. Looks like a nice mixture, when it is lean the color is extremely white with tiny light black spots cause by the pre-ignition.
Dave
located in Chester NH
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1967 1600 in restoration
2013 Arctic Cat F-1100 turbo
Ford F-350 6.0
Ford 9000 puller, Ford 960 puller, Ford 901show, Ford 971 worker, Oliver 70 waiting its turn
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Re: Spark plug color
Yes, but lightly around 300-500 miles. Most were chasing Ted.msampsel wrote:RBMann wrote:I had a lumpy idle and found my main jets at different heights. Front two plugs were rich and the rear looked okay to a little lean. I had set them last year. Now something to watch in the future.
IMG_9118.jpg
Were these plugs ever used? Look like they came right out of the box
RBMann
mechanic on '69-1600(not mine)
mechanic on '69-1600(not mine)
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Re: Spark plug color
Reviving this thread, here are some colors of plugs with 1100 miles. Used wideband to get to a 13.2 reading.
Interesting the "front plug" for each carb shows the most reddish tint.
Seems I needed to add 2 qts of oil too.
Some of it leaks from the rear seal. Oh well, acceleration is great, crisp no stumble. Cruise felt odd, not an obvious stumble, but maybe it was. Certainly happier engine when accelerating.
Interesting the "front plug" for each carb shows the most reddish tint.
Seems I needed to add 2 qts of oil too.
Some of it leaks from the rear seal. Oh well, acceleration is great, crisp no stumble. Cruise felt odd, not an obvious stumble, but maybe it was. Certainly happier engine when accelerating.
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78 911 SC Targa (Severe Oversteer but still loved)
78 911 SC Targa (Severe Oversteer but still loved)
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Re: Spark plug color
What is your gap set to and do you have an electronic dizzy? The gap needs to be set to about .040 with the electronic dizzy. A stumble at cruise is usually a lean miss. I have read that the random things they put into gas these days makes the colors of plugs harder to interpret.
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Re: Spark plug color
Nothing wrong with the color on any of them it seems to me, but it is interesting that you're getting two different colors on plugs that are being fed by the same carb! Different valve lash?
Greg Burrows
'67 2000 #588
Tacoma, WA
'67 2000 #588
Tacoma, WA
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Re: Spark plug color
Does anyone know anything about "glazing" on the plugs? it's hard to see in the pics but the plugs are strangely glossy and glazed looking. Also I'm getting dark on one side and lighter on the other
All the same plug And yes I know there a little rich, I beefed things up on the way to Shasta to keep it from pinging and haven't gotten around to switching back.
All the same plug And yes I know there a little rich, I beefed things up on the way to Shasta to keep it from pinging and haven't gotten around to switching back.
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Oil a little low? Time to get a longer dipstick:)
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Re: Spark plug color
Generally, glazing or glossy deposits on a plug mean overheating of the plug which could result from improper fuel mixture, a plug that's not in proper heat range, etc. Your plugs, though, look pretty normal other than the slightly over-rich condition you mentioned (which could be the cause of the glazing). Inconsistent wear/burn patterns are fairly normal and usually have to do with the configuration of your combustion chamber. Also not a big worry.
I'd just change 'em, correct the AFR, balance the carbs (last pic seems to show inconsistent grades of black) and monitor them from time to time.
I'd just change 'em, correct the AFR, balance the carbs (last pic seems to show inconsistent grades of black) and monitor them from time to time.
MicStable: '68 SRL-311, Z33, SL55 AMG, Highlander-H / Gone: Z34 & Z33 Nismos, Z33-Rdstr, Z33-GT, Z32, Z31 Shiro (R.I.P.), Q45, 6-S30s, D-Prod SRL311 and a bunch of other non-Nissans.