Re-plating and coloring

[Right hand drive]

Rebuilding an older cast zinc Demon. The previous owner took to it with a wire wheel and removed the silver color plating on the bowls. Came up super clean in the ultrasonic cleaner but they are now a dull grey.

Does anyone know what the original plating was on Demon carbs?

Same carb looks like it might have had a few back-fires and burnt off some of the throttle shaft coating. When it peeled off it seemed to be a clear softish flexible coating for anti corrosion and reduced friction in the throttle plate.

What are throttle shafts coated in?

One last question. I have a Race Demon that from the factory are a more gold color than the silver of the rest of the Demon line. When it came out of the ultrasonic cleaner the goldish color was quite patchy and it now looks like it has skin problems.

Does anyone know what gave the Race Demon line its goldish color?

Thanks in advance.

[bigblockmark]

The ultrasonic is a great way to clean small passages in carburetors. My 9 gallon one at 50*C will discolor any carb if left in too long, especially the new tumbled non coated cheapo carbs like brawlers. Those 15 minutes is too long. 5 minutes may be enough. The shiny bowls I just clean manually so they don't lose any luster.

[rgalajda]

Conversion Coatings
Yellow Chromate I believe. Same as old Holleys and Quadrajets made from zinc pot metal. Back then it was Hexavalent chromate available in Clear, Yellow and Olive Drab, which was obtained by ratio of hexavalent. Today some countries have banned Hexavalent chromate and resorted to using Trivalent Chromate with added Dye for colour.
I believe some Demon carbs had clear chromate, but I thought they were aluminum. When you strip old zinc carbs they look like aluminum colour but will grey easily.
My restorations are Zinc plated to all metal parts and then Chromate conversion . The bodies and other parts not being metal are Chromate conversion.
Here is an old Barry Grant carb pic before the Demon

[rgalajda]

Early Demon carb. Again yellow chromate

[rgalajda]

Bowls and metering block stripped with 60 micron glass bead. These were in rough shape . I don't think I will use them.
I don't know if I'm helping here?

[Right hand drive]

Thanks for the replies so far guys. Very informative.

bigblockmark, what cleaning fluid do you put in your ultrasonic cleaner? I trialed a bunch of different cleaners and fluids such as some normal dish washing detergent in the water, vinegar in water, straight gasoline (in a small floating container) straight turpentine and a few other things. Simple Green 4:1 is the best so far. Put the Demon aluminum metering blocks in for 20mins and came out shiny and clean. My ultrasonic cleaner is 40khz.

Below is the bowls in question and the Race Demon that has the one bowl done. You can see on the loose bowls the dull grey areas I’m taking about. The unaffected areas are quite clean with a bit of luster. I’m thinking it’s zinc electroplating but want to be sure. I also want to be sure if the Race Demon is first zinc plated and then dipped in something such as yellow chromate after as suggested so far.



This pic is comparison to an old Gold Claw like rgalajda posted. The Gold Claw has excellent finish and appears to be exactly the same as the Race Demon and what I am after. So what I am seeking is what this finish is. If it’s yellow chromate over zinc plate then I’ll look into that.



Note: body of Gold Claw is matte finish as previous owner had it media blasted including leaving the blue sleeves in there to be blasted (would you believe they were glued in?). It has not been ultrasonic cleaned by me.

[bigblockmark]

I use Simple Green too at about 10:1 ratio. Spice it up more as time goes on. Also I use Distilled water as my well water is hard with calcium.

[ojh]

I've got a pretty decent set of Demon bowls if you need them.

[Right hand drive]

[Right hand drive]

rgalajda

Do you remove boosters to zinc plate and yellow chromate or leave then in?