Zinc--white rust

[VintageMusclecar]

Just thought I'd post this up for anyone who's never seen what happens inside a carburetor when the dichromate finish is compromised. Consider this sort of a "public service announcement", if you will.

I've had a lot of people ask me why they should have their carburetor re-finished even though they don't care that it doesn't "look" good anymore. The thing is, the dichromate finish isn't there for looks, it's there to prevent this from happening;



This is the float bowl of a WCFB Carter a customer just sent in this week. I've seen some pretty crusty carburetors in my day, but this one is right up there at the top of the list. This is what happens when the dichromate finish is compromised and moisture starts to attack the zinc casting itself.

Not very pretty, is it?

Notice you can just barely even see the jets. The powder was close to 1/4" deep in some places. This pic is after I had already dumped out the majority of the loose powder.

By nothing short of a miracle, I was able to save this casting. Needless to say, it was pitted pretty bad, but it survived. Plenty of others haven't. A while back, I had a Corvette 3X2 set in to do. One of the (early dated) main bodys had to be scrapped because the power valve cavity had corroded so badly due to this that you could literally crumble it away with your fingers. There was no way a metering block/plate was ever going to seal against it again.

A closing comment;

This is one of the reasons why, when I restore a carburetor, I refinish all of the casting surfaces, not just the outside ones that show. There's more that could be said on that subject, but I'll leave it at that.

Eric