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Discussion Starter #1
I have been reading a lot about spark plug reading because I don’t think my air/fuel mix is right. I took these out and took pics can anyone help me decipher what I’m looking at. I have a cheat sheet someone shared here but I’m still confused as to what I’m looking at.

I feel like they are all way to black. But I’m not sure. My carb came off a car that was from Colorado so I’m guessing the jets are to small and need to go back to 65s but I’m not sure.

thanks!!!

55F1596B-CD72-4889-ABD6-DBED757136A7.jpeg C4204552-CBE6-4C03-B7F0-6A7DF7DA85EF.jpeg
 

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Discussion Starter #3
Yes! These are the ones I have seen on here. The first one makes me think the are oil fouled but the second one makes me think they are fuel fouled. That’s why I’m so confused.
 

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Oil fouled will be wet. Fuel fouled will be black but sooty.
 

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The page with the photos of spark plugs is from the days of leaded gasoline. With unleaded gasoline and high energy ignition systems spark plugs often look nearly white when all is well. Your plugs being all black looks like a stuck choke or other severely out of tune condition.

The same look can happen when ignition timing is way off because retarded timing causes incomplete burning of fuel, leading to misdiagnosis of a rich mixture being the cause when in fact it is simply lack of basic tune up skills.
 

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I’d say you’re running rich.
Or you ignition timing is off.
Or heat range is too cold.

Get a timing light and set ignition timing first.
Then look at carb settings.
 

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They look pretty rich to me...a well-tuned spark plug will be a light-to-medium brown. It may be worth the effort to get a wide-band O2 sensor setup though...an Innovate LC1 setup is only $140(without gauge, $170 if you want a lightshow). You don't have to have a gauge if you have an old laptop to plug into the thing for tuning purposes....a lot of people permanently install widebands...but they can also be used as a diagnostic and tuning tool that can be removed once you have an engine dialed in(allowing you to use them for multiple cars) All you do is weld in an o2 bung(there is also a non-weld bung available) and plug it when its not in use. If you ask me...$140 to know exactly what your AFR is worth the cost...especially if you have multiple cars that will need at least intermittent fuel tuning.
 

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assuming youre mechanically sound
what kind of coil do you have

you need 1.5 ohm ford style coil with point system

most parts junkies will pul la universal off the shelf which is chevy based at 3.0 ohms

wrong ohms will a few hundred miles foul plugs and give you all kinds of RPM and break up issues

sooner or later the coil will burn up

my car was eating coils with fouled plugs for yrs.......dont ask me how i learned this the hard way
 

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Discussion Starter #9
Oil fouled will be wet. Fuel fouled will be black but sooty.
They are all black but sooty. I was leaning towards that but I wanted confirmation.

I am at 12* initial timing, and 36* total I believe. I don't have my notes written down in front of me. I am going to re-jet back to the 65s the carb came with and set my mixtures back to stock and see where we are at. I have a vac gauge hooked up so I will use that to verify.

Should I leave the timing at 12* and just adjust the mixture screws on the carb until I get the best most consistent vac reading? It's a new Blueprint 302 motor and the 12* is where it idled best at.
 

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Make sure the float level is set properly after you adjust for best vacuum between 10 - 20 degrees initial timing with the vacuum advance plugged and disconnected. Then adjust for best vacuum again. Something is pig rich. I can't imagine jet size as the only problem. 65 primary jets is generally right for a 390, with a 302 I might go down to a 60. Without a fuel / air meter you are not going to be able to tune it very accurately.
 
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Make sure the float level is set properly after you adjust for best vacuum between 10 - 20 degrees initial timing with the vacuum advance plugged and disconnected. Then adjust for best vacuum again. Something is pig rich. I can't imagine jet size as the only problem. 65 primary jets is generally right for a 390, with a 302 I might go down to a 60. Without a fuel / air meter you are not going to be able to tune it very accurately.
Like Royce said... Get your self a air fuel meter get a bung welded in your exhaust and then you will be able to tune it correctly.
 

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Discussion Starter #12
How did people do it when these cars were new? Lol!
Ok I guess that is my next purchase. For now I will set it back to factory and roll with that!
 
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