Spark plug damage

Discussion in 'The Bench' started by 69duce, Jun 22, 2015.

  1. 69duce

    69duce Well-Known Member

    Wanted to see if anyone might have an idea what could be causing this. I have a 69 Buick Electra 430. This is the front end drivers side spark plug (lets call it 1), but then the second back (lets call it 2) has done the same thing. This seems to happen whenever I drive the car hard... fast acceleration (Almost flooring it).

    Attached Files:

    Last edited: Jun 22, 2015
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Detonation from improper ignition timing and/or insufficient octane fuel.
  3. 69duce

    69duce Well-Known Member

    I added an additional image to show the physical damage to the plug. I had them all properly gapped at .030, and it looks as if something may be hitting it.
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Do you know what detonation is? Do you know what it sounds like? If you continue to drive the car hard like that without fixing the problem, you will damage the engine.
  5. Smokey15

    Smokey15 So old that I use AARP bolts.

    Take what Larry says as truth. The man knows what he is talking about. He has taken the time, on many occasions, to give advice to those seeking help. The compression ratio shows to be 10.25:1 for your engine. You should be running premium with a lead additive. I run that in my '62, which has the same ratio.
    BTW, Where is your timing set?
  6. 69duce

    69duce Well-Known Member

    Oh no, I am not questioning any of the advice given. I wanted to make sure I had the proper images showing the damage to the plug.

    I believe the initial timing is set at 12* advanced.

    Thank you again for the continued help.
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I have seen damage like that before. Instead of burning smoothly, fuel can spontaneously explode at the wrong time creating a shock wave in the cylinder. It can fracture the piston and even melt it. Pieces of the piston can fly around and physically damage the plug, or the heat and pressure can do the same. Sometimes, you can see little specs of aluminum on the plug insulator, they look like very small ball bearings and that is from molten bits of aluminum fusing to the plug insulator. The tops of the piston typically look sandblasted after this has been going on for a while. Detonation is one of the most injurious things that can happen to an engine. It can also beat the hell out of rod bearings and crack cylinder walls.

    Over advanced timing or fuel that has insufficient octane for the compression can contribute to it.

    The stock distributor (1111335) supplies 30-34* of mechanical timing. They are meant to be initially timed at 0* (TDC). If your initial timing is indeed 12*, and you have that distributor, your total timing could be as much as 46* at wide open throttle, and that's way too much. Fix that before you hurt the motor. If you look at the pictures you supplied, there looks to be some silver on the white part of the plug although that could be anti seize compound. Did you use any of that? That plug looks like it was hammered.
  8. rogbo

    rogbo Gold Level Contributor

    May be obvious to most, but make sure the initial timing is set with
    the vacuum advance hose disconnected and plugged.
    And that the vacuum advance is working.
    Not sure on your engine if the vacuum advance is manifold vacuum
    or throttle plate vacuum?
  9. 69duce

    69duce Well-Known Member

    "I did not use any anti seize. I will make sure to back the timing off, and I will replace the plug. There has been an instance or two where the car has sounded like it was trying to backfire... But my I have dual glass packs so it's a lot less noticeable.

    So.. Correcting the timing, and could the proper air fuel mixture from the carb have anything to do with the saturation of the spark plug with fuel?

    I I know I have no idea what I am talking about... But I truly appreciate all the direction. I am trying to figure out a basis of the issue so I could start to eliminate the issues I'm having.

    Thanks much
  10. DaWildcat

    DaWildcat Platinum Level Contributor

    Hi Jahred,

    I had the same problem with my 1967 Electra, same engine as yours. In the 1980's I could hear the "spark knock" when I opened the throttle. At that time I didn't know that driving like that could cause damage to the engine.

    I had some big engine damage, and maybe you can't hear it because of the loud glasspacks exhaust.

    Please consider moving your distributor for less timing so you do not harm the engine any more.


  11. srb

    srb Well-Known Member

    You've never heard anything that resembles throwing marbles when accelerating fast? It sounds a little bit like that.
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Take a look at the distributor, around the circumference just under where the cap meets the body of the distributor. Look for the part number. If the distributor is original to the car, it should be part number 1111335. If you have that distributor, it should be timed initially to 0* (TDC). I'm wondering if you ever put a timing light on the engine. It doesn't sound like you know the timing for sure. You have to know.

    In your pictures, there is clearly some silver on the white part of the plug. That is most likely aluminum from the piston.

    I wrote a timing thread years ago. Ignition timing has to be one of the most misunderstood subjects among car enthusiasts. The only time an engine runs at the initial timing is when you are sitting at a traffic light. Once the engine RPM rises above idle, the mechanical and vacuum advance systems inside the distributor ADD TIMING to the initial setting. That is what you MUST consider.
  13. 69duce

    69duce Well-Known Member

    I am starting to understand what I must be doing to the engine. I do have a timing light. The degrees go to 10 on the harmonic balancer I believe so I estimated it at 12* initial timing with the vacuum advance disconnected. I do have a timing light, and initially when I had it set at 0* the car seemed as if it barely could stay running, acceleration was sluggish, so I took to the internet. I remember looking up some stuff before and reading that old buicks could handle "more timing" and I set it at 8* at the time. 2 weeks ago I decided to look at the carb air/fuel mixture, and when adjusting that I guess I thought it would be smart to advance it just a little more.. (I just want Lucy to go faster haha. I have now confused myself, which has led me to seek your expertise.

    I have checked the other plugs and they look good...

    So as a plan of action:
    I will replace the damaged plug. Set the timing to 0* with the vacuum advance disconnected (right?). Is .030 the gapping I should be using? Also I use AC Delco - single platinum spark plugs.. Is that advisable?

    What next?
  14. 69duce

    69duce Well-Known Member

    I want to say I may have heard that before. I wish I hadnt, but I believe I have.
  15. 69GS400s

    69GS400s own amusement ride!

    set the dial on the timing light to 30*, plug the vacuum and rev it until the line on the balancer stops moving - that is your total mechanical timing.

    What it reads at idle means nothing once the rpms are above idle
  16. 69duce

    69duce Well-Known Member

    What if my timing light is old school? And doesn't have a dial?
  17. DaWildcat

    DaWildcat Platinum Level Contributor

    Use your old-school timing light and set the timing to zero, or if that's not enough to keep it running smoothly, go 4 advanced or more, but for goodness sake, keep your foot out of it. I hate to say it, but when the spark plugs look that bad, there might very well be more damage.

    Fill the tank with 93 octane, and then read Larry's thread about how you can mark the balancer in order to use your timing light for setting TOTAL ignition timing.

  18. 69duce

    69duce Well-Known Member

    Understood, and thank you. I will do this today.
  19. DaWildcat

    DaWildcat Platinum Level Contributor

    Glad to hear it, and sorry if some of us come across too sternly, we just want to help you avoid what some of us have already been through. Most of all we're hoping you can enjoy the car for many more years!

  20. 69duce

    69duce Well-Known Member

    Listen... If my dad was around he would be yelling, and not via email. I bought the car for $900 and have put and exhaust, couple gaskets, and a new top on it. Less than $500 in parts. I have been enjoying the hell out of it, but I just need a little direction.
    So I appreciate it. And keep it coming

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