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Old 05-28-2023 | 11:33 AM
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Default Reading plugs

Swapped out the 1050 88 sq jets and had ProSystems put another 1050 together with 78's square. Had the boat out a couple weeks back and ran it pretty hard, but had some idle time getting back to the dock/trailer. I understand that will change the reading vs WOT, but more curious how the plugs look overall? From what I can see, I think they look pretty good. Previously, the plugs were black/wet very rich. 3/5 look a little richer than the rest (still dry), but nothing too horrible to my untrained eye.


Last edited by 540Fever; 05-28-2023 at 11:57 AM. Reason: Correct link to pictures.
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Old 05-28-2023 | 02:24 PM
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I think you would have to run it at a steady RPM for several minutes, shut the key off, then check the plugs.
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Old 05-28-2023 | 02:41 PM
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Understood in that… but curious if the plugs show and negative signs that would still remain from detonation etc

thanks
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Old 05-28-2023 | 04:24 PM
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Only thing that would show signs of how detonation would be a cracked porcelain.
If you want you know the condition at WOT or Cruise you need to run at that speed for a few minutes and then shut it down and read them. Once you've idled for a few minutes the coloring has completely changed.
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Old 05-28-2023 | 04:29 PM
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Only thing that would show signs of how detonation would be a cracked porcelain.
If you want you know the condition at WOT or Cruise you need to run at that speed for a few minutes and then shut it down and read them. Once you've idled for a few minutes the coloring has completely changed.
If your plugs were wet you need to straighten out the idle adjustment. If the plugs are wet the walls are wet and your killing the rings because it's washing the oil away. The idle adjustment is easy and must be done after fully warming the motor up.
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Old 05-28-2023 | 07:30 PM
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Sometimes detonation will leave tiny specs of aluminum on the porcelain
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Old 05-28-2023 | 07:42 PM
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Originally Posted by GPM
Sometimes detonation will leave tiny specs of aluminum on the porcelain
This

You will see small specs of silver or black. If you cracked a plug, you have severe detonation.

Invest in a cheap otoscope.

A good video on reading plugs.

Last edited by underpsi68; 05-28-2023 at 07:44 PM.
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Old 05-28-2023 | 10:00 PM
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Originally Posted by GPM
Sometimes detonation will leave tiny specs of aluminum on the porcelain
Yep. I've seen tiny little balls of alum on the porcelain. A bright light and a magnifying glass helps a lot.
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