Bad Carbon Fouling

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74desertduster

74desertduster

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So I have been dealing with a poorly running slant for a week or so now.

I stopped for gas one day and poof, it started running really badly. I'm sure it was slowly getting worse and reached a tipping point that particular day.

Prior to that I have recently changed the plugs, cap, rotor, all the normal tune up items including coil. Ran great for a few days and then, bam...poop.

It has acted like a carb problem to me. I have adjusted the idle mixture and curb idle as best I can. Idle mixture screw has very little impact until almost seated. Curb idle is not so high as to be taking the idle mixture out of the process.

Timing has been by ear as I have no timing marks and have yet to get a vacuum gauge.

So today I pulled the plugs out, thinking they were probably fouled with something based on the very poor running and lack of power. Had Champions in there and got NGK ZFR5N to put in.

The plugs, all 6, are extremely carbon fouled. Like I have almost never seen. Put in the NGK's and runs great again.

Would this most likely be an overly rich problem with the Holley 1920?
 

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This hit me last night. When I got the car the previous owner had the choke rod disconnected. I ran it like that for the first week or so and then after I had done all the tune up stuff, reconnected the choke rod and it seemed to be working properly.

I am thinking now that the previous owner was on to something and it was sticking closed, thus causing all my rich running. I have taken the rod back off and with the new NGK plugs it runs like a different engine now.

So hopefully it was the choke and not something internal with the carb. Had some blue oil smoke this morning until it warmed up but as poorly as it had been running the past 10 days or so, it could just be clearing out some residual stuff in the chambers that had not been burned off.
 
Did you take the metal ring washers off each new spark plug before installation? That's important.

You'll want to fix the choke. Send me a PM and I'll send you a line on a new choke thermostat that'll work correctly. Could also be that there's nothing the matter with the choke thermostat, but the choke pull-off (vacuum operated "flying saucer" at the top rear of the carb) is faulty or its link missing or bent.

Keep an eye on the new spark plugs; if they carbon up you've still got some detective work to do.
 
Yes, took the washers off the plugs.

The choke thermostat seemed to be working properly which is why I went ahead and put the rod back on it. Will need to check the pull-off.

I did find an electric thermostat which I would like to use eventually....once I get things stable a bit.
 
74desertduster said:
This hit me last night. When I got the car the previous owner had the choke rod disconnected. I ran it like that for the first week or so and then after I had done all the tune up stuff, reconnected the choke rod and it seemed to be working properly.

I am thinking now that the previous owner was on to something and it was sticking closed, thus causing all my rich running. I have taken the rod back off and with the new NGK plugs it runs like a different engine now.

So hopefully it was the choke and not something internal with the carb. Had some blue oil smoke this morning until it warmed up but as poorly as it had been running the past 10 days or so, it could just be clearing out some residual stuff in the chambers that had not been burned off.
Click to expand...
You may want to check for oil dilution too if it's been running rich for a while. That may be contributing to the "blue smoke".....that and maybe valve seals.....
 
Ya, had just done an oil change prior to all this. Will check out the oil and give it a good look/smell.

Need to find a dipstick and tube for it too....
 
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