Paint inside of carb?

[Commander Toasty]

Doing a rebuild on the carb and wondering if you guys paint or otherwise treat the interior when you rebuild?

Mine clearly shows that it had previously been painted inside, and I found bits of flaked paint blocking jets. Seems like an obvious problem with non-specific paint.

On the other hand with no paint it will rust in some places, particularly now with the high alcohol fuels carrying water.

It seems some kind of protection is indicated...but what?

[ford1]

if you have to paint the carb, do only the outside, nothing good can become of painting inside the carb

[ken ct]

Do not coat the inside of carbs with anything. ken ct.

[Ron in Quincy]

I have to disagree, I coat the inside of the Zenith and Holley float bowls with Tool Mates Red Insulating Epoxy Coating, its gasoline resistant; have used this for years with no problem. Use the same product to reinsulate generator and starter armatures and field coils, this is what it is actual designed for but being gasoline resistant it keeps down rust from forming inside the carburetor bowl.

Ron

Like Tom says, I mask the jet threads.

I do not like WD 40 as it draws moisture; people with guns quit using it years ago, when wiping down guns and then putting them away; it was found the WD 40 drew moisture and guns would start rusting, even in a gun safe; and especially in a gun case.

[Tom Endy]

I spray paint each of the two casting separately. I mask off the areas I don't want painted. I paint the inside of the intake tunnel after I mask off where the cap jet sits and push a piece of paper towel into the jet hole for the main jet. I mask off where the venturi sits. I do not paint the fuel reservoir or the two mating surfaces. I do not paint the top flange or the throat where the throttle plate sits. Anything with threads is either masked off or has a piece of paper towel shoved in it.

I use a length of threaded stock screwed into the castings as a wand to hold while painting the castings.

When the paint is dry I spray the bare metal areas with WD-40 to prevent rust.

Tom Endy

[Bill in NJ]

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What kind or make of paint do you use??

[dave in australia]

To prevent rust on the inside of zenith carbs, I use de-oxidine, which converts the top few microns of the surface to iron phosphate and is rust resistant. As it is not an added coating, there is nothing to flake off and block any pasages. It also gets into all pasages where no paint can get into, also protecting those pasages as well. It will not stop rust if the carb is left in the weather, but provides enough protection when in the engine bay. The outside is still painted, with engine enamel. There has been some conversations on this board previously about what paint to use and the general consensus was RC model paint. I went to the local RC store and the owner said he uses engine enamel because it was cheaper and still methanol proof, so thats what I use and no paint has been washed off by petrol yet.

[Tom Wesenberg]

I brush paint (2 coats) inside and out on my carbs and use PACTRA Areo-Gloss JET BLACK 63. The paint looks correct, stays on and is fuel proof. I've used some tank fulls of the crap gas (you know, that ethanol crap) and after 6 years most of the paint has gone from the inside of the fuel bowl, but the paint's all intact in the throat and on the outside of the carb.

[Tom Endy]

This paint is fuel proof.

Tom Endy

[Commander Toasty]

The thing about fuel proof is it is not chip proof.

I certainly agree that the mating surfaces should be bare, and that means a break point for the paint, and paint does not like that. Paint likes to be a membrane, and any discontinuity encourages chipping. Thus with the mating surface being bare this might offer too good a place for flaking even though the paint can resist gas. I do like the idea of a converter - Dave can you give more info on de-oxidine?

[dave in australia]

Originally Posted by Commander Toasty

Dave can you give more info on de-oxidine?

It is used by painters before a coat of etch primer. It maybe what is called metalprep by some, but I'm not sure of that. The product I use is available from PPG and is called de-oxidine624. If used, you can see a slightly blue tinge to the bare metal after it has been used.