Spark plug is turning black

SEA MAN

MEMBER
1979 DODGE VAN
V8
2WD
AUTOMATIC
3,500 MILES

Soot, carburetor issue.

Sunday, May 24th, 2020 AT 6:33 PM

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Can you provide a little more detail with what we can assist with? Unfortunately "soot" isn't enough to know what you need us to help with. Thanks. We will wait to hear back.

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Sunday, May 24th, 2020 AT 6:39 PM

SEA MAN

MEMBER
2 POSTS

It is a 1978 Dodge 440 4 Barrel Charter it is in a American Clipper 1979 RV the carburetor is facing to the rear not the front like normal carburetors and as follows I put new plugs, point distributor and new PVC voltage regulator alternator and new oil and also new filters twice. What is happening is the spark plug is turning black I know that this is caused from the rich gas so I turn the idle screws down in the carburetor. When you're looking down inside of it the right side has a lot of fuel moving in the bottom but the left side does not it only comes out the fuel port. So I'm wondering if the pump or the injectors or the needles in the carburetor are bad and that's why I'm getting so much soot this carburetor is extinct they don't make it anymore? They don't make anybody who makes it any more they're going to make a duplicate for it they don't make a replacement for it. So now I'm wondering what would be my next alternative to repairing the RV? Also with that in mind it is a charter carburetor is called a thermoquad it has only three sets of numbers on it that I could find. There's a 6-2 363 I believe it is an H 32 and like I said it is a thermoquad if this is my problem then I need to find an alternate and of course I'm not a parts expert, but I can definitely repair automobiles. I have been repairing them for over 45 years. So with that being said thank you for your reply I await your answer.

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Monday, May 25th, 2020 AT 8:47 AM

KASEKENNY

MECHANIC
18,907 POSTS

Long story short, yes. The right side of this carb should be the primary side. The left is the secondary side. Basically the carb is a two barrel carb except in high fuel demand situations. Normally high RPM.

You are on the correct path. If you have adjusted the needles all the way down and it is still too rich then the needles are most likely worn and cannot cut the fuel off. You see this with the fact that the plugs are black. That means too much fuel.

At this point, if there are no repair parts, your options are to upgrade to a more modern carb that will fit this engine. For that I would contact one of the major venders like Jegs, Holley, Edelbrock and tell them what you have and they can provide a carb that will fit along with the proper adapter plate and spacer if needed.

I have run into this exact thing on my father in laws 1956 Lincoln Mark II. Someone replaced the original carb with a Stromberg Aeroquad. Stromberg makes carbs for airplanes and motorcycles, oh yeah and one year they made enough four barrel carbs to fit two model years of Buicks. And that just so happens to fit my father in laws 1956 Y Block. However, there are no parts or replacements. My option is to buy a rebuilt original for almost a $1000 or go with a modern carb.

It is a tough choice but if you put a modern carb on it, you can pretty much just turn the key and it should start right up.

Let me know if you have questions. Thanks

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