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Need a read on my spark plugs

 
Old 06-07-2019, 03:57 PM
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Blue73Shark
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Default Need a read on my spark plugs





1973 L82 4sp original engine, 66,100 miles, set up to run per Lars papers. Runs strong and fast but needs a tune up as the last one was 10 years and 9000 miles ago. I drive it about 1100 miles per year and it burns about 1.5 quarts of oil during that time. Attached is a picture of the plugs I pulled today.
What are they saying?
Thanks.
Fran

Last edited by Blue73Shark; 06-07-2019 at 07:45 PM. Reason: Side shots of 4 & 8 added
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Old 06-07-2019, 04:23 PM
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7T1vette
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Plugs, cylinders, distributor cap and/or plug wires for #4 & #8 have some problems. The others look to be relatively clean and burning well with no oil or contaminant build-up on them. What you have on #4 & #8 COULD be due to faulty (or not completely seated) plug wires, damage on dist cap contacts for #4 & #8, of plug damage (internally).

Just my .02....
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Old 06-07-2019, 04:39 PM
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#5 is a little odd looking. Color looks good but the electrode looks to be eroded.

I wonder if your valve seals are off on #4 and #8? Your oil consumption isn’t too bad but not negligible either.
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Old 06-07-2019, 04:46 PM
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If the engine is original and never disassembled, the valve stem seals need replacing and may be the problem with 4 & 6 as well as the excessive oil consumption. The others appear to show soot on the plug bases, too.
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Old 06-07-2019, 06:36 PM
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CanadaGrant
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It's kind of hard to tell with a straight on top shot like that instead of one from the side but I agree with the others. 4 and 8 look like oil so maybe valve seals. If it was even on all it would indicate wear but it isn't so I would start with a compression check and if all are up then look at valve seals. Cheap and easy to do.
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Old 06-07-2019, 07:46 PM
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Originally Posted by CanadaGrant View Post
It's kind of hard to tell with a straight on top shot like that instead of one from the side but I agree with the others. 4 and 8 look like oil so maybe valve seals. If it was even on all it would indicate wear but it isn't so I would start with a compression check and if all are up then look at valve seals. Cheap and easy to do.
Thanks for the suggestion. Added side shots of 4 & 8 to the original post.
Fran
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Old 06-07-2019, 09:09 PM
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jackson
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I agree w/ the others on valve stem seals ... some 46 years & 66K ... they should be split crumbly and perhaps a few're gone.

May also be more than a little wear on guides/stems themselves.

VS Seals fairly easy to R&R on motor in-car ... check guide/stem wear at same time.

-edit-
in addition to seals, may also be intake gasket leakage ... sucking oil into some runners.

Last edited by jackson; 06-07-2019 at 09:13 PM.
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Old 06-07-2019, 10:32 PM
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My first thoughts were oil too. Too clumpy and thick to be just soot.
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Old 06-07-2019, 11:43 PM
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Couldn't really see the detail on 4 & 8 until you re-posted the close-ups. Looks like oil build-up. But they are so junked-up, spark is limited [or non-existent], so oil residue would continue to build-up. Valve stem seals is a good possibility, although I would expect several of the others to be worse than they presently show, if that were the ONLY problem. I think you have some weak spark issues as well on 4 & 8.

TEST: Clean up plugs 4 & 8 and move them and their respective wires to 2 & 6 (and vice versa). Run it a while, then look at all the right-side plugs. If 4 & 8 still look bad, the problem is isolated to the cylinders; if 2 & 6 look bad, the problem is with the electrical components. If you get "something else" results, you likely have problems in both areas.
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