weber manifold coating

[tomkirkcis]

I am rebuilding my webers and was thinking about the finish of my manifolds. I know there are some benefits of ceramic coatings on exhaust to control heat transfer. Is there any benefit to ceramic coating the intake ? . Anyone ever explore this avenue or am I just being stupid. tom

[911pcars]

I say no. Atomized fuel from the carbs iis pretty cool (temp-wise), and warm intake manifolds contribute to additional atomization to the A/F mixture (that's good).

For a cost-benefit ratio, save your ceramic coating budget for something providing more return effects. Some folks use powder-coat paint, but that's merely for finish-longevity instead of any performance advantage.

Sherwood

[Steve@Rennsport]

There are some thermal dispersant coatings that work very well on these cars, but I would only use them for performance or racing applications........

[tomkirkcis]

Steve,

It is a 3.2 twinplug, high compression, ge60, ported, weber 46 type motor. Would there be a real benefit to the heat dispersal coating and what would it cost?

[piggdekk]

I know this is an old thread, but reading here and there I couldn't find an answer to my question.
I need to get my manifolds (for Zenith's) painted because someone painted them in red with a rattle can (!!!!). I will deliver the manifolds to a place that will blast them with walnuts, and then I would like to have them power coated. Does the black need to be gloss or matt? since my manifolds where painted in red, I don't have any reference.
luca

[HawgRyder]

Wouldn't powder coating lock in the heat?
There are types of paint that are heat dissapating...but it normally involves some type of repeat application with heat setting in between coats.
Perhaps anodizing might be a better way to go?
Bob

[piggdekk]

Anodizing sounds complicated for magnesium and for what I read is used only as a base layer prior to painting. As for locking the heat, yes, powder coating would probaby act as a heat barrier, but this soft magnesium needs to be protected anyhow, so I rather do it right instead of having the paint peeling off in a short time. For the isolation I haven't decided yet if I should put 2 phoenolic isolators or only one. When I took the carbs off my car I've found phoenolic isolaters only on one carb, the other one had none!!!
luca

[HawgRyder]

I guess if you are insolating the manifold from the head...whatever finish yo put on will do.
Magnesium requires special handling (prep and coverage).
What about the spray on stuff recommended for fans?
It's a protectant...right?
Bob

[KTL]

Powdercoating is said to be complicated for magnesium too. Reason being is because it tends to out-gas. So the Mg needs to be prepped a bit to ensure your powdercoating doesn't fail. Incidentally I saw yesterday Richard Newton posted something about trailer wheels which lead me to his blog site. He's got some nice, simple information on wheels and it mentions Mg

Car Tech Stuff: Vintage Race Wheels

Problem with paint is that you typically need a specialty or two part paint to ensure it is fuel resistant. Ceramic coating or powder coating is fuel resistant. Just have to be sure neither ceramic nor powder gets on the gasket surfaces. It's a real pain to remove since its so hard, ceramic more so than powder.

Also, Mg can be anodized. It turns out sort of green-ish and you of course must have it done by someone who knows what they're doing.

Lastly, I had powdercoating on my aluminum weber intake manifolds. I saw no ill effects from it.

Keeping the manifolds warmish, but not too warm is a good thing like Sherwood said. The main reason for the phenolic spacers on the manifolds is to prevent heat transfer to the carbs via the manifolds, that can boil the fuel in the carb's fuel wells which can then cause an engine fire. The combination of vent tubes in the top covers and phenolic spacers under the manifolds is intended to avoid the fuel boiling issue.

[911pcars]

I'll have to correct my earlier statement regarding ceramic vs powder coating. Many shops that apply ceramic coating, do so on smallish parts like gun components and knives. Thus, the cost to ceramic coat a few pieces might be less than the minimum many shops charge for powder coating.

Prepping parts to coat (degreasing, bead or sand blasting, etc.) might save some labor.

Coating the intake manifolds will protect the base metal from oxidizing. That includes rattle can paint too. Resistance to fuel is a plus in this area.

Powder or ceramic coating will reduce heat absorption from the surrounding area.

I'm not sure powder coatings are as resistant to chemical damage compared with ceramic coating.

Some ceramics can be applied on a DIY basis with minimal equipment. Not all ceramics have to be baked.

Sherwood

[chris_seven]

All very complicated.

There seem to be several conflicting issues.

PMO for example make thermal insulators to isolate manifolds from the head and keep temperatures low.

I assume that this is so that the carb will meter more effectively but many water cooled cars use heated manifolds.

Fuel will atomise more effectively when it is warm but not so warm as to cause it to vapourise as then we seem to have a range of other problems

Air inlet temps need to be low as air density and hence power improves.

That said I believe that early manifolds were painted in a PU paint and chromating magnsium as a primer is a good idea.

We use DOW 1 to chromate then paint with Dupont Imron at 50% gloss.

[BURN-BROS]

The plastic insulators are a necessity for the U.S. market these days as the fuel percolates in the carburetors at very low temps.


Oil compaines are re-introducing certain chemicals into the fuel to make more profit as they sell by volume not weight. These chemicals return to a gas state and very low temps. They can get away with it as the majority of cars are fuel injected and do not exhibit the problem. Keeping the carbs at ambient temps solves the problem.

I had a car that had a 30% increase in fuel economy after I installed an isolator under the carb.

[piggdekk]

I guess it is a general consensus that phenolic spacers are needed, I believe I read a thread from Grady suggesting to use 2 of them on top of each others. Even if they were detrimental in terms of performance I would use them anyway just to make sure that when I turn off the car heat doesn't soak into the carbs and boils the fuel.
In fact I found something really odd in my carbs. The left bank had spacers, while the right one didn't, I have no idea why. Anyway the bank without spacers had very different dirt in it. Both had a bit of rust, but the one without spacers had some kind of transparent cristals both in the fuel chambers and in the top, just above and around the fuel needles. It may be that one of the 2 carbs was cleaned and spacers installed, but maybe there is a possibility that the cristals were the leftover from the boiled fuel. Any input on this?

As for the coating if I can I'll have Chris doing my manifolds, I do like the idea of having them prepped and coated the way they should. In the meantime I'm checking locally if there is an helicopter workshop that can do it following the method described by Chris.
thanks for all inputs
luca

[chris_seven]

I have just made a bagful of Tufnol spacers and gaskets to suit but generally for in house use.

They were waterjet cut earlier today and should be with me in the next day or two.

[KTL]

Powdercoating is fuel resistant from what I can tell. My carbs had a small leak on one of the accel pump housings for who knows how long before I noticed it. The manifold that was being leaked upon showed no signs of the powdercoat lifting or softening.

Another example is the fill plate on my fuel cell that was powdercoated blue and it withstood the fuel exposure for several years. The cell was quite old when I got the car in 2009. I had to clean up the bottom mating surface to get the cork residue/chunks off. I used Permatex gasket remover and that was a big mistake- lifted the powdercoat off like paint stripper causes paint to bubble. So I stripped the rest of the powdercoat and tried to repaint it with store bought rattle can paint. No joy. Engine enamels and other high heat paints were not fuel resistant.

[911pcars]

To add another layer of heat insulation for the carbs, one could install add'l phenolic (or equiv.) spacers between the carb and manifold. They would be appropriately sized for the throttle bore (40. 46. etc.) and the "matching" inlet side of the manifold.

Sherwood

[chris_seven]

Magnesium is not great for Powder Coating and adhesion is generally poor depending on the powder, chromating is always considered an essential pre treatment befor powder coating mag components.

Fuel resistance will also depend on the material used for coating. Some of the polyesters are quite good but other grades will soften and are quite poor.

Some of the better materials such as Rilsan would be completly reistant but it may be difficult to find a supplier and cost would be high.

[911pcars]

Originally Posted by chris_seven

Magnesium is not great for Powder Coating and adhesion is generally poor depending on the powder, chromating is always considered an essential pre treatment befor powder coating mag components.

Fuel resistance will also depend on the material used for coating. Some of the polyesters are quite good but other grades will soften and are quite poor.

Some of the better materials such as Rilsan would be completly reistant but it may be difficult to find a supplier and cost would be high.

My anecdotal experience; I powder coated my factory mg. intake manifolds in 1997 or thereabouts and they were perfect up until I sold them (w/engine) last year (2012).

Might be a good idea to double-check up-front with the planned powder coating service.

Sherwood

[KTL]

Good info guys.

Just wanted to add that i'm not endorsing powdercoat. I actually don't like it much at all.

My '79 engine was purchased with a metallic blue fan, same blue on upper valve covers, same blue on short Weber manifolds. Finding some gasketed areas that needed trimming/chipping bothered me, along with no longer liking the blue color.

So I stripped the powdercoat. Found that Citristrip brand paint stripped kicked the crapola out of the powdercoat. Boy was I happy to be rid of that bloo color....

Before

After


PMO "Short" Manifolds- Weber 46

[piggdekk]

I ended up having the manifolds (magnesium) bead blasted and powder coater in black. I followed your instructions and had them pre-heated prior to spray the powder on to avoid gassin up. Looks like it was a good idea since in few spots one can see some very small (less than half mm) "bubbles". Overall howerver the adesion looks to be excellent. We've used epoxy powder coat hoping for best resistance to fuel.



In the next picture you can see the tiny "bubbles" I was referring too. They show like white dots, but it is just an effect of the light.



Now I will have the 2 surfaces milled flat and I should be ready to put them back in.
Question: the interior and top and bottom surfaces won't be protected. I reckon they are not likely to get in touch with water, but still, should I protect them with some kind of penetrating oil? Finding gibbs penetrating oil in Spain is quite a challenge .

thanks
luca