`Porcelain on plugs looks burned!

Discussion in 'Troubleshooting & Diagnosis' started by willscamaro, Oct 12, 2012.

  1. willscamaro

    willscamaro Veteran Member

    103
    0
    Apr 29, 2012
    Panama City, Florida
    Hello this is a 79 Camaro 350 engine and I changed plugs about 3 months ago, but now they look burned. I put in original type plugs, AC Delco gapped correctly but now they failed. Any ideas?
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

    20,639
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    Apr 14, 1999
    Bismarck, North Dakota
    Are you having any issues with how the engine runs? If not, some discoloration on the porcelain is normal.Oil fumes and dirt burn onto the porcelain as the car gets used.
     
  3. willscamaro

    willscamaro Veteran Member

    103
    0
    Apr 29, 2012
    Panama City, Florida
    Yeah, the car is not running well at all. It's running rough, knocking and really eating gas, maybe needs carburetor adjustment?
     
  4. ^this is probably your issue. Did you use the same part number plugs? Have you modified anything lately before it started running bad?
     
  5. willscamaro

    willscamaro Veteran Member

    103
    0
    Apr 29, 2012
    Panama City, Florida
    I put in specific plugs and other parts such as plug wires, distributor cap and rotor button, that is recommended for this vehicle. We have had this car less than 6 months and previous owner did not keep up with routine maintenance, also first oil change,the oil was black and full of metal particles so am trying to put back in good shape
     
    Last edited: Oct 13, 2012
  6. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    8,191
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    Jun 22, 2003
    Endicott, NY
    I'd like to see a picture of the spark plugs and show what cylinders they came from.

    IF they are BLACK then the engine is running too rich. If they are a light brown, then that's perfect. If they are white, that's TOO lean which is just as bad as too rich if not worse because there is the possibity of menting a piston.


    What carbuetor is on the motor? Quadrajet? If so, then it may need a rebuild. To rebuild it you need a rebuild kit, a float, some Hysol Epoxy, fuel filter, and (if NOT in the kit) a carburetor to intake gasket and an accelerator pump. TAKE PICTURES AND NOTES AS YOU TAKE IT APART! Be careful when you assemble it not to bend or jam up the metering rods.

    I use Hysol Epoxy http://www.aircraftspruce.com/catalog/cmpages/loctiteHysol.php to seal the welch plugs in the bottom of the main body of the carburetor. Scotchbrite the area around the welch plugs. Build a dam around the welch plugs to contain the epoxy. Use just enough epoxy to cover the welch plugs but not too much that the base won't bolt to the main body. Use a hair dryer on a low heat setting to get the Hysol to set quicker just don't overheat it though.

    BTW, I used Hysol Epoxy at IBM to seal 316 SS tanks that held some NASTY chemicals and it withstood them. I've used Hysol Epoxy on carbs for years with no failures.
     
  7. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    8,191
    1
    Jun 22, 2003
    Endicott, NY
    I forgot to have you check the throttle shaft to carb base fitment. IF it is sloppy, then you need to either get a new carb or have bushings installed in the base.

    What a worn base causes is a vacuum leak that makes the engine run lean at idle and screws up the vacuum signals of the carb = poor perfoming carb.
     
  8. willscamaro

    willscamaro Veteran Member

    103
    0
    Apr 29, 2012
    Panama City, Florida
    Thanks so much Cardinal, I really appreciate all the help! The porcelain on the plugs are black and the carburetor was changed to an Edelbrock which i have heard from others that 's not a very good one. Any ideas on that?
     
    Last edited: Oct 13, 2012
  9. mgoad1971

    mgoad1971 Veteran Member Lifetime Gold Member

    2,471
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    Jul 29, 2011
    Houston, Texas
    I still look at this chart every time I change my plugs!!




    .[​IMG]
     
  10. Cardinal

    Cardinal Veteran Member Lifetime Gold Member

    8,191
    1
    Jun 22, 2003
    Endicott, NY
    Here's my opinion on carburetors:

    Quadrajet is THEE best carburetor for a stock or mild engine on a Qjet/Spreadbore intake. Even Hot Rod Magazine had to admit that the Qjet give the best performance and fuel economy.

    Edelbrock/Carter AFB is the next best carburetor for a stock or mild street engine. The one problem with them is that the float height and drop on them out of the box is WRONG! Go to the Edelbrock website, get the float height and drop for your carb, and follow the directions.

    Holley is the best carburetor for a performance engine because it takes the least brain power to get it to work = put block off plugs in place of the power valves, up-jet it a couple of jet sizes, and usually, you're in business. I do not like the single feed Holley carbs because1) there is NO external float adjustment, 2) eventually the feed tube that goes between the front and rear float bowls will leak (not a matter of If but a matter of WHEN it will leak). IMHO, the words Holley carburetor and economy carburetors are not synonymous.
     

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