#5 and #7 Plugs are White - Chevelle Tech
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post #1 of 7 (permalink) Old Oct 22nd, 13, 3:39 AM Thread Starter
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#5 and #7 Plugs are White

Hey fellas, I took the Chevelle out for a spin today and noticed some grey smoke coming out of the drivers side exhaust. This prompted me to check the plugs. All plugs looked normal except for #5 and #7 which were fairly white. My first guess would be a vacuum leak in the intake somewhere in that vicinity. What is your opinion?

Mike Smith
72 Chevelle, LS 6.0 LQ9 4l80e
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post #2 of 7 (permalink) Old Oct 22nd, 13, 9:55 AM
Glen
 
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Re: #5 and #7 Plugs are White

I don't see an intake vacuum leak causing white smoke. With 5 and 7 being next to each other, I'm guessing a head gasket leak.
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post #3 of 7 (permalink) Old Oct 22nd, 13, 10:08 AM
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Keith
 
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Re: #5 and #7 Plugs are White

Grey smoke...hmmm, does it have that antifreeze smell?
Check coolant level. If coolant level seems o.k...
Have you run a compression test?
If compression test seems o.k. then post photos of #2 and #6, along with #5 and #7.

What distributor? What plugs? How much advance? What carb and intake? Iron or aluminum... Etc.,

But before you bother with all those details, do the coolant/compression thing first.

Just my opinion,

Keith

Owner: World's Fastest 66 Chevelle - really...it's really really fast since I put on that chrome differential cover
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post #4 of 7 (permalink) Old Oct 22nd, 13, 12:32 PM
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Re: #5 and #7 Plugs are White

Unleaded gasoline? White IS normal.

Got the #5 and #7 plug wires reversed?

What's the outside temperature? We typically get a heap of "white/grey smoke" questions in the fall, when folks aren't used to seeing exhaust vapor condensing in cool air.

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post #5 of 7 (permalink) Old Oct 22nd, 13, 12:40 PM Thread Starter
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Re: #5 and #7 Plugs are White

Well im from Phoenix so we are not really having "fall" weather lol. The temps are still in the mid 80s. The smoke doesnt look like vapor, its more heavy looking.

I always thought that tan plugs were normal? Why would 5 and 7 be white but not the others?

The distributor is MSD, with RC12YC champion plugs, 10 degrees of mechanical advance, 28 initial, holley 750 street hp DP, RPM airgap intake, and Edelbrock aluminum heads.

Mike Smith
72 Chevelle, LS 6.0 LQ9 4l80e
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post #6 of 7 (permalink) Old Oct 22nd, 13, 3:47 PM
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Re: #5 and #7 Plugs are White

Quote:
Originally Posted by smitty454 View Post
I always thought that tan plugs were normal? Why would 5 and 7 be white but not the others?
Tan plugs WERE normal...years ago, or when using racing gas that has lead.

White and clean porcelains are pretty normal now, unless the engine has incorrect fuel mix, oil consumption problems, or the plugs are ancient enough to have finally collected some color.

Have you done a compression test? Leakdown test? Cylinder-balance test? Maybe those two cylinders aren't running, so the plugs look like new.

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post #7 of 7 (permalink) Old Oct 22nd, 13, 5:33 PM Thread Starter
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Re: #5 and #7 Plugs are White

The plugs do not look new. The ground strap is white but the porcelain is brown. I haven't done any tests yet.


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Mike Smith
72 Chevelle, LS 6.0 LQ9 4l80e
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