Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

True? False? Maybe? On. Some choke parts

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Burd:
I think all my linkage is gold.   I’ll have to look at it. 

Shiny:

--- Quote from: Cliff Ruggles on September 23, 2022, 04:35:05 AM ---I see the entire carbs zinc plated so it looks like a big gold nugget....talk about UGLY.

Even with that said I've had customers bitch when we colored the castings correctly and combinations of bright zinc, yellow chromate, and green on the parts like the factory did.  They were expecting a big "gold nugget" based on their Internet "research".

So I ended up doing most of them as shown in the pic below unless the customer specifically asked for factory "colors" on the associated parts......FWIW....

--- End quote ---

If "factory correct", I assume you used a clear chromate conversion instead of the iridescent on zinc-plated parts.  But how would you color the die castings?  Is there a "hobbyist-friendly" conversion coating that ends up looking like the original on the die-castings or have those old chemistries become outlaws?

Cliff Ruggles:
There is not "hobby friendly conversion coating" that I know of.  When I was doing them here we used a "recipe" based on how the factory did them.

There is a significant learning curve with coloring castings.  Surface prep, temperature, time, chemicals used, etc. 

Results also vary some even using the exact same "recipe".  This happens because the base materials changed over the years.  Early carbs tend to color darker than later years.  Carburetors that were commercially "remanufactured" can also be difficult to color as many got an "acid bath" as part of the cleaning process.  This removes some of the zinc from the castings and they don't react the same way when coloring them as castings that didn't get that treatment......

Shiny:
Thanks for the reply.

I know it can be "artsy"...

And it makes sense that a casting that has been acid-cleaned would selectively lose zinc-rich phases from the surface and change the way the conversion coating reacted.  Did you zinc plate those in the photos?

I could also guess the alloys changed and would not all react the same.  For example, did a Rochester casting use a different alloy and respond differently than a Carter casting?  Did the casting alloy change over the years?

All I know is a stripped casting is easy to spot and practically, will be more corrosion-resistant and cosmetically more stable with a conversion coating.

Cliff Ruggles:
I do not zinc plate main castings and airhorns.

Carter and Rochester castings are not the exact same material although Carter made them under contract for Rochester.

Carter castings are "soft" in comparison, don't age as well, and tend to color "deeper" than Rochester units from the same period.

General rule for coloring is that the earlier they are the darker they will be from the coloring process....

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