I've thru every thing but the kitchen sink at it.

[Doug Larsson]

I have a 1973 charger 400 bb 2bbl auto.
So one day I noticed my car idle great and ran great when it was cold on the way to work ( I work graveyard) but gradually (3days) when coming home it was colder out it would fall on its nose and it was harder to get up to speed to get on the freeway it would clean out and then run fine. I decided to change the spark plugs and noticed a lot of black on them and they didn't even have 500 miles on them I didn't notice any wet oil residue on the spark plugs though just really black. I changed the spark plugs and started up and idle great everything but soon as I put it in drive and I started going it started backfiring and popping I couldn't even get it up to speed. So I've decided that maybe it needed new plug wires coil cap and rotor. The carburetor is brand new and it ran fine before all this happened I checked the timing and the timing was fine. I think the valve guides might be going because I'm getting allot of black soot out the tail pipe when it's cold which got me thinking maybe that's why the spark plugs are so black i tried leaning it out a little but it still kept doing it. I'm about ready to take it to a guy I know that has a hot rod shop and have them look at it because I'm pretty much at my wits end trying to figure out what's going on with this thing. Any help or suggestions are greatly appreciated thank you.

 

[1967coronet440]

From your description and pictures of the plugs it's running rich. More engine specs would help Carb+jetting, cam, intake...

 

[khryslerkid]

Might be as simple as some dirt in that big Ole 2bbl. Float level a bit high? Think simple first!

 

[Fran Blacker]

Choke problem?

 

[dieseldazzle]

You probably cracked a plug, improper gap or crossed a plug wire if it was running fine before you touched it other than just

 

[69roadr]

I would take it to the hot rod shop since they know what they're doing

 

[Beekeeper]

I would take it to the hot rod shop since they know what they're doing

 

[Doug Larsson]

From your description and pictures of the plugs it's running rich. More engine specs would help Carb+jetting, cam, intake...

2bbl Holley ND 2577 don't know the jetting off hand stock cam stock intake.

 

[MoparLeo]

Are you running the factory Champion spark plug ? Valve guides/ leak oil...blue/grey smoke. Rich fuel mixture..black smoke ....Don't throw any more parts at it until you learn to diagnose the problem correctly. If you don't know the difference between burning oil and a rich fuel mixture, you are just throwing your money away. Take it to a shop with a good reputation and let them do the diagnosis. At least you will get some kind of warranty if it fails to fix your problem.

 

[Yatzee]

I have a 1973 charger 400 bb 2bbl auto.
So one day I noticed my car idle great and ran great when it was cold on the way to work ( I work graveyard) but gradually (3days) when coming home it was colder out it would fall on its nose and it was harder to get up to speed to get on the freeway it would clean out and then run fine. I decided to change the spark plugs and noticed a lot of black on them and they didn't even have 500 miles on them I didn't notice any wet oil residue on the spark plugs though just really black. I changed the spark plugs and started up and idle great everything but soon as I put it in drive and I started going it started backfiring and popping I couldn't even get it up to speed. So I've decided that maybe it needed new plug wires coil cap and rotor. The carburetor is brand new and it ran fine before all this happened I checked the timing and the timing was fine. I think the valve guides might be going because I'm getting allot of black soot out the tail pipe when it's cold which got me thinking maybe that's why the spark plugs are so black i tried leaning it out a little but it still kept doing it. I'm about ready to take it to a guy I know that has a hot rod shop and have them look at it because I'm pretty much at my wits end trying to figure out what's going on with this thing. Any help or suggestions are greatly appreciated thank you.

View attachment 496671 View attachment 496672

For sure you're very rich on your mixture. Plugs will be black after periods of long idling but should clean up during long hard runs at higher speeds. This is obviously an "air/fuel" ratio problem and requires a meter to diagnose just how severe it is. I note one statement you made: "The carburetor is brand new and it ran fine before all this happened" so I'm thinking that therein lies your problem. Perhaps the carb is having a hard time maintaining the A/F ratio and if you could substitute it for another you may or may not see a difference. Got a buddy who would allow you to mount his "known to be good" carb on your engine? You not only need decent A/F ratios but also proper engine temperature and a clean burn. Too much fuel, too small a carb (yes that can cause it when it comes to metering fuel), poor spark due to low secondary voltage, timing and wrong plug heat range, and premature plug fowling that can't clean itself up are all possible issues. You need an experienced diagnostic done. Kitchen sinks can get expensive after a while.

 

[65wgn440]

If you combine what Fran blacker & dieseldazzle suggested, you might find your problem(s).

 

[Doug Larsson]

Thank you every one for your suggestions I'm going to check the spark plugs again before I take it to a shop. I was planning on replacing the spark plug wires in the coil and the rotor and cap anyways but not like this but that's alright I need to do it anyways.

 

[Doug Larsson]

Are you running the factory Champion spark plug ? Valve guides/ leak oil...blue/grey smoke. Rich fuel mixture..black smoke ....Don't throw any more parts at it until you learn to diagnose the problem correctly. If you don't know the difference between burning oil and a rich fuel mixture, you are just throwing your money away. Take it to a shop with a good reputation and let them do the diagnosis. At least you will get some kind of warranty if it fails to fix your problem.

Yes I'm running the Champion spark plugs.

 

[Ron H]

In addition to good advice posted, you could have an accumulation of carbon deposits inside motor valves/rings that "sometimes" can be cleaned out successfully with engine cleaner like Seafoam or even running some Marvel oil additive for awhile. Some times this can be diagnosed by checking the engine vacuum and compression testing. I had a poorly functioning valve in my car causing wicked vacuum and acceleration stumbling and used Marvel for a while and got decent results. These are simple/cheap things to do.

 

[oldbee]

You probably have an electrically heated choke, I'd check like Fran says to make sure it's opening. I'm surprised ranger16 hasn't chimed in ; chokes are often forgotten about.

 

[Yatzee]

I have a 1973 charger 400 bb 2bbl auto.
So one day I noticed my car idle great and ran great when it was cold on the way to work ( I work graveyard) but gradually (3days) when coming home it was colder out it would fall on its nose and it was harder to get up to speed to get on the freeway it would clean out and then run fine. I decided to change the spark plugs and noticed a lot of black on them and they didn't even have 500 miles on them I didn't notice any wet oil residue on the spark plugs though just really black. I changed the spark plugs and started up and idle great everything but soon as I put it in drive and I started going it started backfiring and popping I couldn't even get it up to speed. So I've decided that maybe it needed new plug wires coil cap and rotor. The carburetor is brand new and it ran fine before all this happened I checked the timing and the timing was fine. I think the valve guides might be going because I'm getting allot of black soot out the tail pipe when it's cold which got me thinking maybe that's why the spark plugs are so black i tried leaning it out a little but it still kept doing it. I'm about ready to take it to a guy I know that has a hot rod shop and have them look at it because I'm pretty much at my wits end trying to figure out what's going on with this thing. Any help or suggestions are greatly appreciated thank you.

View attachment 496671 View attachment 496672

I'm inclined to believe you would know if the choke wasn't opening. You would notice the black rich smoke and smell of throat slicing fumes. If you suspect this to be an issue, lock the choke open, clean the plugs and start again on your diagnostics.

 

[Doug Larsson]

In addition to good advice posted, you could have an accumulation of carbon deposits inside motor valves/rings that "sometimes" can be cleaned out successfully with engine cleaner like Seafoam or even running some Marvel oil additive for awhile. Some times this can be diagnosed by checking the engine vacuum and compression testing. I had a poorly functioning valve in my car causing wicked vacuum and acceleration stumbling and used Marvel for a while and got decent results. These are simple/cheap things to do.

Cool great idea thank you I did a vacuum test a couple weeks ago and it was fine I had a compression test last year when I purchased it and it read:
#1,2,6 140 lbs
#4,8 138 lbs
#3 125 lbs
#5 130 lbs
He checked all cylinders 2 times to make sure.

 

[Doug Larsson]

You probably have an electrically heated choke, I'd check like Fran says to make sure it's opening. I'm surprised ranger16 hasn't chimed in ; chokes are often forgotten about.

I tested it the other day it reads enough ohms and the I tested the heating element it did get hot but I never witnessed the bi-metal spring expand after 5 min. I would expect it expand before 5 min.

 

[Doug Larsson]

I'm inclined to believe you would know if the choke wasn't opening. You would notice the black rich smoke and smell of throat slicing fumes. If you suspect this to be an issue, lock the choke open, clean the plugs and start again on your diagnostics.

Correct when the motor is warmed up the choke valve is open .

 

[Doug Larsson]

I would take it to the hot rod shop since they know what they're doing

I should explain that comment they have been in business for 25 years the do a lot of muscles cars some are in hot rod magazines I have seen a lot of there work over the years .I had them do my roof and did and excellent job . Not all hot rod shops are bad you just have to do your home work talk to other customers and and see there work before making a decision on who you trust.