What do you think of these spark plugs?

[GTamas]

I need your advice.
Do you think this is a 30-year old stock plug, or maybe it was replaced already 15-20 years ago?

And what do you make of its condition?
To me it looks very clean, maybe even too clean?

Car is stock. The gap is around 0.042 inch. Haynes manual tells me it should be 0.052 inch?
What do you think?

 

[RAU03MACH]

clean burn ok
no oil blackness very good

 

[white95]

clean burn ok
no oil blackness very good

I will agree with this, those are healthy looking plugs.

 

[r3dn3ck]

Electrode and strap look great. It’s old but not nearly worn out. Tens of thousands of kilometers remaining.

 

[GTamas]

Thanks guys!

 

[Daryl]

I would, at minimum, give them another shot and put them back in. Drive it and “feel/listen” how it’s firing and responding at different levels of acceleration. They do look surprisingly good for being that old, which, if they haven’t been changed in that # of years can be a sign of a very solidly-built motor! Count your blessings there!

Reminder: don’t forget to put a dab of anti-seize on the threads!

Spark plug wires still in good shape??

 

[GTamas]

Spark plug wires still in good shape??

I replaced them ca. 15 years ago with Taylor 8mm ones. I need to replace one now because it touched the headers and got some small cracks on it. Rest is in good shape.

 

[white95]

I replaced them ca. 15 years ago with Taylor 8mm ones. I need to replace one now because it touched the headers and got some small cracks on it. Rest is in good shape.
View attachment 33667

Find a location that’s very dark and watch them with the engine running. If the outer insulation is degraded enough you’ll be able to see signs of arcing.

 

[96blak54]

Or run your hands along the wires while its running.....youll find the bad spots!

 

[Wood's 5.0]

They look good to me as well.

 

[CobraRGuy]

Although I would agree that these plugs indicate that the engine is running good, keep in mind that spark will fire most easily from a sharp point. Your picture shows that the end of the center electrode is somewhat rounded. If you compare this to a new plug you'll see that they have sharp edges on the electrode.
I've been using Motorcraft Iridium plugs in my engine. They're considerably more expensive, but last a long time. I've found them on sale for much lower cost, and Motorcraft offers coupons and rebates that make them even more affordable.
Just my $0.00000002 worth...

 

[ttocs]

Find a location that’s very dark and watch them with the engine running. If the outer insulation is degraded enough you’ll be able to see signs of arcing.

it is a whole lot easier just to grab the cable that you think is bad and run your hand down it. If it is bad, you will know....

 

[GTamas]

Bought new plugs. Same as factory and current ones: Motorcraft AF42C (SP450X set).
I will replace them tomorrow. Tonight I'm checking the gaps.
What I noticed, the one that I removed from the engine has a gap of .043.
The new plugs are .04
Factory spec should be as far as I know (and Haynes confirms) .052

So I think the plugs were replaced sometime already, but the gap was not set at factory specs. Do you think this is a big difference? What other problems can too tight gap make other than not optimal fuel efficiency, lower performance?