WCFB Rebuild - Gray Putty Residue

[Joe L.]

Re: WCFB Rebuild - Gray Putty Residue

Chris, That looks very familiar. But didn't Holley admit they had some plating issues at some time and replaced many carburetors under warranty? I recall that some time ago.

Joe, Do you know what the actual metal is in these old WCFB's. It looks like pot metal. Isn't that aluminum and zinc?

Rich

Rich------

Pot metal is a term used in the vernacular for zinc diecast. Zinc diecast is an alloy of mostly zinc. I don't know, off hand, what the other alloying metals are but they make up a small percentage of the material. Zinc diecast is relatively inexpensive to cast and is widely used for many things.

Most carburetors, including WCFB's, are mostly zinc diecast material as far as air horns and float bowls go . Throttle bodies are often cast iron (e.g. Rochester 4GC) or aluminum (e.g. Holley 4 barrel, Rochester Q-Jet). The exception is Carter AFB's which I believe are mostly aluminum throughout.

Both aluminum and zinc are highly reactive metals and will be rapidly attacked when exposed to corrosive materials.

[Richard M.]

Re: WCFB Rebuild - Gray Putty Residue

Rich------

Pot metal is a term used in the vernacular for zinc diecast. Zinc diecast is an alloy of mostly zinc. I don't know, off hand, what the other alloying metals are but they make up a small percentage of the material. Zinc diecast is relatively inexpensive to cast and is widely used for many things.

Most carburetors, including WCFB's, are mostly zinc diecast material as far as air horns and float bowls go . Throttle bodies are often cast iron (e.g. Rochester 4GC) or aluminum (e.g. Holley 4 barrel, Rochester Q-Jet). The exception is Carter AFB's which I believe are mostly aluminum throughout.

Both aluminum and zinc are highly reactive metals and will be rapidly attacked when exposed to corrosive materials.

Joe, The more I think about this, the more I am now concerned about safety. If in fact that gray matter is dissolved zinc, I am now concerned that this carb body material thickness has been compromised. In other words, if the thickness of the area from the highest fuel level down to the base has lost material, has the body become thinner? The matter was approximately 1/8" thick over the entire floor of the body.

If so, and the body has lost material, a rhetorical question.........

Could this be a bomb in the making? What if it continues with this material loss? Could the body become a sieve and become porous to the point that ALL of the fuel in the body could leak out onto a hot manifold and cause a major fire?

When I had it here yesterday I should have taken some thickness measurements and compared to a known good casting. I'm going to contact my friend before he reinstalls this back on the car.

Rich

[Chris H.]

Re: WCFB Rebuild - Gray Putty Residue

Rich, funny you should mention leak / fire. In the photo of the fuel bowl you can see 2 tiny holes that were the source of a leak. Fortunately no fire.

[Duke W.]

Re: WCFB Rebuild - Gray Putty Residue

I recall a "gray putty" that built up at the bottom of the oil filter housing on my SWC back in the day. I cleaned it out periodically, but never dried a sample for closer inspection. My best guess is that it was lead oxide residue from blowby that got into the oil and then settled at the base of the filter housing, but I never noticed it anywhere else in the engine or fuel system... just the bottom of the oil filter housing.

[Richard M.]

Re: WCFB Rebuild - Gray Putty Residue

Rich, funny you should mention leak / fire. In the photo of the fuel bowl you can see 2 tiny holes that were the source of a leak. Fortunately no fire.

Scary.

I recall a "gray putty" that built up at the bottom of the oil filter housing on my SWC back in the day. I cleaned it out periodically, but never dried a sample for closer inspection. My best guess is that it was lead oxide residue from blowby that got into the oil and then settled at the base of the filter housing, but I never noticed it anywhere else in the engine or fuel system... just the bottom of the oil filter housing.

I've seen that gray oil sludge in canister before too.

I just took my 2x4 WCFB down from the 4 post lift. I've been running mostly E10 for the last 8 years. I'm afraid of what I may find.

Rich

[Patrick H.]

Re: WCFB Rebuild - Gray Putty Residue

I've seen that gray oil sludge in canister before too.

Rich

I found a bunch of gray sludge in my Austin-Healey's oil when I changed it right after my purchase in late 2015. I asked the previous owner what he might have put in as an additive, and he didn't recall putting in anything.

I was thinking this weekend when I drove it to my new home that I need to see if there is more sludge in there now.

PH

[Jim D.]

Re: WCFB Rebuild - Gray Putty Residue

I just took my 2x4 WCFB down from the 4 post lift. I've been running mostly E10 for the last 8 years. I'm afraid of what I may find.

Rich

I wouldn't worry. I've been running nothing but E-10 in my 2x4 WFCB's for DECADES with no issue.

[Richard M.]

Re: WCFB Rebuild - Gray Putty Residue

I wouldn't worry. I've been running nothing but E-10 in my 2x4 WFCB's for DECADES with no issue.

I hope it's so. I'm tied up working on a intermittent stalling "only when at normalized temp" problem on the wife's V12 that's driving me crazy so I won't tear into my 2 x4 carbs until I fix that other nightmare. I wish I could post for some help with that Etype here as I bet somebody here would help me nail it down. The 2 jag forums I'm on are not very helpful.

Maybe a nice "Non-Corvette Automotive Diagnosis Help" Section here would be nice. I recall one thread got by here a while ago as it was a Chevy Truck and it was really fun reading an learning.

[Terry M.]

Re: WCFB Rebuild - Gray Putty Residue

Rich et al:
I believe the reason that the bodies of carburetors are plated is to prevent exactly what you are seeing in the zinc reacting with the chemical additives in gasoline. The carb manufacturers don't plate the zinc castings for decoration. It is for protection. When that plating degrades internally the results are what you are finding.

[Joe L.]

Re: WCFB Rebuild - Gray Putty Residue

Joe, The more I think about this, the more I am now concerned about safety. If in fact that gray matter is dissolved zinc, I am now concerned that this carb body material thickness has been compromised. In other words, if the thickness of the area from the highest fuel level down to the base has lost material, has the body become thinner? The matter was approximately 1/8" thick over the entire floor of the body.

If so, and the body has lost material, a rhetorical question.........

Could this be a bomb in the making? What if it continues with this material loss? Could the body become a sieve and become porous to the point that ALL of the fuel in the body could leak out onto a hot manifold and cause a major fire?

When I had it here yesterday I should have taken some thickness measurements and compared to a known good casting. I'm going to contact my friend before he reinstalls this back on the car.

Rich

Rich-------


This is one of the reasons that I don't like rebuilt carburetors. Folks think that any carburetor can be rebuilt to be "good-as-new". If I ever thought that way, I gave up that notion a long time ago. The fact of the matter is that carbs do wear out and carb "cores", even rare and properly date coded examples, may be just a piece of scrap metal. I suppose for certain carbs which are absolutely unobtainable new, one just has to go with a rebuild and cross their fingers. As I've said many times before, nothing makes a car run like a NEW carburetor. NOTHING. That's why I've accumulated many NOS carbs [none for sale].

[Joe L.]

Re: WCFB Rebuild - Gray Putty Residue

Rich------


Assuming the material is a metal, it would be possible to identify it using atomic absorption spectroscopy. Of course, we don't have that available to us and it's not worth sending it out. However, there is a bit of qualitative analysis that could be done.

Zinc melts at 786 degrees F. So, if using the heat of a torch that can attain that temperature, a little bit of the dried material melts into a blob, we'll pretty much know it's zinc. Lead melts at an even lower temperature (620 degrees F) but I really don't see how this could be lead.

[Richard M.]

Re: WCFB Rebuild - Gray Putty Residue

Terry,

Good point. Do you know what type of plating was used on the WCFB's? I recall the outside of the carb was plated but unsure if the inside was. I suppose it would have to be as it was a immersion process. If it was Zinc plating, then maybe that alone is what has deteriorated.

Joe,

I would agree about rebuilt carburetors as I have seen many with problems. Nothing like new, as long as the supplier makes a quality product. I had some nightmares with 3 Holley 2300's a while back. Poor quality castings and internal flaws. A rebuilt set of 2300's about 5 years ago had their share of issues too. Perfect restoration and rebuild at a outside facility. One problem....the restorer did not replace the float on the center carb and reused the original. After a few months of use, guess what failed. A pinhole in the float caused a tough problem one day with obvious flooding. Other issues with rebuilt 2300's... They have a common problem with warped baseplates. This is nightmarish and a time consuming repair, if one can locate good flat usable baseplates.

As far as the gray material, I saved the powdery substance for future analysis. Good idea about the melting point. But I think you're right, it's zinc. It's non magnetic and has some white particles mixed in. I did some web research and there is much to learn about this corrosive mixture causing this issue. I still have concerns about this particular carburetor and if it has lost too much material. What I saved is only about a teaspoon now that it's dried out. It was much more when it was in a puttied state, probably because when mixed with fuel it was like putty..

Rich

[Terry M.]

Re: WCFB Rebuild - Gray Putty Residue

Terry,

Good point. Do you know what type of plating was used on the WCFB's? I recall the outside of the carb was plated but unsure if the inside was. I suppose it would have to be as it was a immersion process. If it was Zinc plating, then maybe that alone is what has deteriorated.

Joe,

I would agree about rebuilt carburetors as I have seen many with problems. Nothing like new, as long as the supplier makes a quality product. I had some nightmares with 3 Holley 2300's a while back. Poor quality castings and internal flaws. A rebuilt set of 2300's about 5 years ago had their share of issues too. Perfect restoration and rebuild at a outside facility. One problem....the restorer did not replace the float on the center carb and reused the original. After a few months of use, guess what failed. A pinhole in the float caused a tough problem one day with obvious flooding. Other issues with rebuilt 2300's... They have a common problem with warped baseplates. This is nightmarish and a time consuming repair, if one can locate good flat usable baseplates.

As far as the gray material, I saved the powdery substance for future analysis. Good idea about the melting point. But I think you're right, it's zinc. It's non magnetic and has some white particles mixed in. I did some web research and there is much to learn about this corrosive mixture causing this issue. I still have concerns about this particular carburetor and if it has lost too much material. What I saved is only about a teaspoon now that it's dried out. It was much more when it was in a puttied state, probably because when mixed with fuel it was like putty..

Rich

Sorry Rich
I have no experience with WCFBs. Actually I would only be guessing with Holleys and Q-Jets; but I know it when I see it. To paraphrase a famous quote.

[Domenic T.]

Re: WCFB Rebuild - Gray Putty Residue

Rich,
I agree that something reacted with the pot metal.

Dom

[Domenic T.]

Re: WCFB Rebuild - Gray Putty Residue

Rich,
Like to say one more thing. I find the exact grey crap about 3/16" thick in the oil pans, stuck to the bottom. Not one but every one I have opened, they are aluminum and Magnisium. I can get a large soup can out of every one. The only engine I didn't find it in was one I rebuilt and used Valvoline racing oil in it. All the others had mineral ashless dispersant oil. The gray stuff also built up in a capped place in the crank which caused corrosion and required periodic checks.
I can't see anything similar to your situation other than the exact grey matter I find. Using Valvoline oil stopped it in my situation, but lessened my oil changes from 25 hrs to about 1/2 before the oil needed to be changed. The only suspicion I had was the lead in the fuel that seperated from the carbon that blew down the side of the pistons.
Could it be the protective coating in the new tank that makes it's way thru the stone filter?

Dom