What the heck is this??

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tkelley72

Well-known member
Joined
Feb 1, 2013
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Location
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My Car
72 mustang convertible
Hoping someone can tell me what this gray powder is in my metering block? Everything I have read says that white residue is from Ethanol but this stuff is gray and literally caked in there blocking everything up. For some history, I have been having carb. issues for a couple of months now. Since I have never rebuilt a carb. I payed someone to do it for me. I know he took it apart and cleaned it because I saw it disassembled. Long story short, the carb. has less than 2 hours total run time on it when my idle problem resurfaced. With help and personal direction from forum member "Basstrix", I took the plunge and pulled the carb. apart and found this. Obviously I'm no expert, but how could this much stuff build up in my carb. after only 2 hours of run time and more importantly what is it and where did it come from? I know the gas in my tank is old probably bad but I did pump some into a plastic bottle to see if there was any obvious trash from the tank. Nothing, no rust or sediment that I could see. I have the carb. thoroughly cleaned with carb. cleaner and blown out with compressed air. It's ready to test to see if my idle problem is solved once and for all but I don't want to run the engine until I can figure out what this gray powder is, where it came from and will it happen again or is there a way to prevent it going forward. Hoping maybe someone out there has an answer. I'd be asking "Basstrix" if I could since he's been such a great help but unfortunately for me he's on a "cruise" catching some rays somewhere right now. Thanks guys....
 

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As I remember, years ago, someone called that “rust flour.” It is the byproduct of tank rust. That’s all I know. If you can, remove the fuel tank and clean throughly. The new fuel with added water makes rust firm faster. You should also change your in line fuel filter.

I’m sure others will chime in on this subject.
 
I've rebuilt dozens of Holley (and other brand) carbs. I have *never* seen gray powder residue like that in any of them.

I would clean that out and blow all of the passages in the carb out really well with carburetor cleaner. Disconnect the fuel inlet hose from the pump and feed the pump with fresh gas from a can. If that remedies some of your issues, then it's time for a tank cleaning or replacement.
 
tkelley, since that is the air bleed and main air "emulsifier well" side of the block no fuel passes thru there, only air. My guess is someone was extensively running the carb without a filter in a dirty environment like off-road or dirt track. Just my guess. In any event as the above members stated a deep clean is awaiting your carb.
 
tkelley,
are you using a carb air horn gasket between your carb and air cleaner ?
it almost , almost looks metallic, is your air cleaner steel or aluminum ?.
could this possibly be from your air cleaner rubbing on the carb body ?
I have seen a substance similar to this in a Holley electric choke housing before.
wonder if this substance is conductive, that would tell you a lot about where it came from.
Hopefully you saved this gunk so you can test it a little.
Boilermaster
 
I'll take a shot that the galvanization on the interior of the fuel tank is the culprit of this "grey matter" and suggest, along with Hemikiller a replacement tank and a through flush of all lines or an upgrade to SS lines...
Thanks, Jay
 
Dudes,
Cleveland Crush is correct that no fuel resides in this channel, it is the
main air well.
If fuel was supposed to be there, there should also be this crud in the fuel filter and float bowls, this is an air problem and not a fuel problem.
Boilermaster
 
Ok, let me respond to the questions and answers that you guys provided. First, let me clarify that the carb. was cleaned and rebuilt 2 months ago. Since then the car has only had no more than 2 hours of run time on it, mostly sitting in my garage trying to get the thing to idle. Since I could not achieve that, I completely tore it down again this week and that is when I found all the gray power in the metering block. The car was only on the road actually driving for less than 5 miles. I have since blown out all passages and holes on every part of this carb. with compressed air and carb. cleaner. The only place that I noticed any gray powder was in the metering block.

1. Fuel filter is clean
2. Fuel inlet filter id clean
3. Pumped about 8 oz. of fuel into a clear plastic bottle. (from the tank, through the fuel pump) Let it sit overnight and inspected. No particles or sediment. Poured it through a coffee filter and no sediment on the filter.
4. The car nor the carburetor has ever been exposed to a dirty environment of any kind. Especially after the initial rebuild. I literally only drove a couple of miles home.
5. I run the Cobra Oval air cleaner with a K&N filter which is in good condition. Yes, I also run with the horn gasket.
6. I did not save any of the gray powder, but I agree that it looks a bit metallic, basically like graphite.
7 The bowls did not have any of this stuff or white stuff usually attributed to Ethanol. The finish in the bowls look like the plating has been eaten away over time. You can wipe your finger across and get a small amount of residue from that but I suspect it is just from bare aluminum? (see attached photo)

So, if there is no fuel in that area to cause this and it is in fact an air issue, where on earth is this gray, graphite looking stuff coming from after such a short, sanitary run time? How could air cause this? I want to finish putting this back together but don't want to be right back where I started with this stuff after another 2 hour run time. I'm no carb. guy by any stretch of the imagination, but I was a mechanical engineer for 40 plus years. To me, this is kind of mind boggling! Hope this will trigger some more ideas. Thanks for your help and input guys!
 

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tkelley72,
was there anything between the secondary metering plate gasket and main body ?.
 
It does look like a graphite type material. :unsure: What does the "rebuilder" have to say about it? You might want to just try it again and see if that crap returns...
 
Kelly I've also noticed the bowl screw threads are coated in this material, thus a likelihood the carb was assembled in a dirty environment or maybe cleaned in dirty carb cleaner solution. If that's positively not the case, we are back to this powdery material getting sucked through the air bleeds.
 
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My carb. is an 80457-1 which is a 4160. It has the goldish finish. The secondary side looked perfectly fine, no gray stuff. I did notice that both bowls are missing the finish inside. (I've attached a photo for review. ) One thing to note is that I know that the initial rebuilder used "brake cleaner" to clean the carburetor. He went on about how he liked the fact that brake cleaner dried quicker. I just got off the phone with a tech. guy from Holley. It was his opinion that it is likely that the chemical in the brake cleaner had a chemical reaction to the plating and broke down and that is more than likely what I am seeing. Makes sense to me especially based on the condition of the inside of the bowls. I have cleaned them out again with carb cleaner but am thinking about soaking the bowls and the metering block in something to remove any residual chemicals that may still be present. Any ideas on what I could soak them in? Would also be interested in your opinions regarding what the Holley guy said. Thanks again for all the input.
 

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    primary fuel bowl.JPG
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My carb. is an 80457-1 which is a 4160. It has the goldish finish. The secondary side looked perfectly fine, no gray stuff. I did notice that both bowls are missing the finish inside. (I've attached a photo for review. ) One thing to note is that I know that the initial rebuilder used "brake cleaner" to clean the carburetor. He went on about how he liked the fact that brake cleaner dried quicker. I just got off the phone with a tech. guy from Holley. It was his opinion that it is likely that the chemical in the brake cleaner had a chemical reaction to the plating and broke down and that is more than likely what I am seeing. Makes sense to me especially based on the condition of the inside of the bowls. I have cleaned them out again with carb cleaner but am thinking about soaking the bowls and the metering block in something to remove any residual chemicals that may still be present. Any ideas on what I could soak them in? Would also be interested in your opinions regarding what the Holley guy said. Thanks again for all the input.
If that's the case, the "guy" who did your carb rebuild should a) buy you a new carb and b) find something else to do, he doesn't know what the f he's doing.
 
Is it possible that the rebuilder used anti-seize on the float bowl screws?
Wiping off anti-seize that squeezed out when compressing the gaskets and inadvertently pushed into the air bleeds could explain that.

Looking at the Fuel bowl bolts, I would ask the same question. The threads and shanks appear to have a very similar-looking coating on them, and that does look like anti-sieze compound. Clean that out, reassemble and try running it again - I bet it'll clear up.

And don't buy a carb or have one rebuilt from wherever you got that one again.
 
I planned on cleaning the bowl screws before reassembly. The carb is the one that was on the car when I bought it 20 years ago. The guy that did the rebuild was just someone that was recommended to me from a friend that had used him for other work and was satisfied with the results. The only reason I had someone else do the rebuild is that I had never done one and didn't want to screw things up. Guess that backfired huh? Live and learn the hard way. At least now thanks to the guidance of member "Basstrix", I now know how to do a rebuild myself. I've cleaned the bowls with carb cleaner and plan to soak them in hot water and Dawn dish soap, then blow it out to remove any possible brake cleaner residue that may be left over. (unless someone thinks that's a bad idea) Thanks to all for your input. It has been very helpful!
 
Did you burn up a fan belt in the past? The first picture looks like fan belt debris. It likely was not cleaned during the rebuild, it doesn't really look new. The second picture with the gray looking coating looks like bad fuel. You might want to clean out your fuel line and tank. Use Rust911 on the tank.
 

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