Achieving the mill finish on 4.9L valve covers?

I'm going to refinish the valve covers on my Bora's 4.9L.

- The black crinkle paint is plain to see.
- Right now the raised lettering is just hand-painted with a contracting silver and I wish to restore them with the proper 'milled' finish.

Does anyone know anything about the milling technique or type of machine used originally?

I have aluminum primer and 'crinkle' paint ready to go. I deduce the original sequence was to paint the crinkle paint first and mill the raised areas on a machine last. I'm not sure how they set up the milling machine to avoid the oil-filler neck on that cover, but I can discuss it with my machinist. The other 3 covers seem "easy" to put across a light planer at my machinist's shop.

Thank you,
- Art

 

I did mine a lot of years ago but as I recall I took a piece of sand paper glued it to a block of wood and just sanded it off after painting. The original job was pretty shabby as are the castings in general. But a good thick very wrinkly (is that a word?) paint finish hides all the junk on the covers and the heads. The style of wrinkle is controlled by the thickness of the paint and the amount of heat. Let them age a while before putting them back on maybe a couple of weeks. Otherwise it can tear when bumped by a tool. Once the engine gets hot it will fully cure. You will smell it for a while.

 

Art & Bob,

The way Bob desribed it was also the way Maserati did this.
I did my engines the same way. Before sanding the paint down I did carefully cut/scrape the paint of the letters with a painter's knife.

BTW: I used VHT wrinckle paint and did not use a primer on the aluminum. Sits on there nicely, on my Vignale Spider meanwhile 27 years...

Success,

Ciao,

Bart

 

I did a Ghibli set last week.

1. Painted the cam covers using the MIE wrinkle finish paint. I find the paint from the rattle cans do not work as well. I put loose leaf paper hole protectors so that paint does not get where the cam cover washers seal. You can find these at most office supply stores.

2. Let the covers dry overnight.

3. Put the covers in the oven for 30 minutes at 225 degrees Fahrenheit

4. Wait another day

5. I used a DA sander with 80 grit paper. It makes the job very easy to do. Put masking tape over the ignition sequence numbers if you do not want them sanded.

6. Remove the paper hole protectors.

Ivan
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Yes, I used VHT as well, circa 1990 so I don't know how good it is now?

I don't remember if I primed or not?

The ones done on my Espada just before I bought it in 2010 were just terrible as it's all flaked off. Was it because of bad prep? I don't know.

When I did mine I ran the covers though the dishwasher a couple of times. Can't do that for the heads ...

My 84 Biturbo got the same treatment in red a bit earlier. It's tuff stuff but the red has turned color a bit now. If you use a self etching primer it HAS to be for high heat as well.

For my 96 Ghibli Open Cup I tried power wrinkle. It's fine grain and is holding up ok though the car gets such little use. The trouble is that no matter how well you prep the parts and mask of the underside and openings the GD powder coating places insist on glass bead blasting it and they got those beads & shards all over the inside of the covers.

A very bad idea!

 

So how has the MIE stuff been holding up? You have any long term examples?

 

There are several threads about wrinkle finish in the Ferrari section.
Yes the MIE paint holds up well but when ever you paint Aluminum it is necessary to clean the Aluminum with aluminum metal prep before painting if you want the finish to last. I have had good results with VHT but the MIE paint is better if you have a spray gun. I let the finish set a day and then scrape most of the paint off the raised areas with a single edge razor blade. Then as Ivan suggest bake for 30-40 min at 225 or leave it in the sun on a warm day. BTW I only do this on warm days +75 and preheat the parts in the sun for 30 min. If you use the VHT you need at least four coats. Let each coat flash or dry for 30-40 min before applying the next coat.

 

Great, as I am about to do this.

Question though, I have problems getting the old wrinkle paint off. What did you use?

Best,

Jack.

 

Thank you for sharing gentlemen, plenty of good information as always… Sounds not very difficult to accomplish.

I'll ask MIE where their crinkle paint comes from. I've used an aviation industry product by Tempo from Aircraft Spruce. Maybe MIE's is more appropriate.

Ivan, did you sand or bead-blast the aluminum surfaces at all to get 'tooth' before repainting?

Prep: I refinished the instrument panel on my airplane years ago. It was a very smooth/glossy aluminum. I scotchbrited it to scuff the surface, then halfheartedly glass-beaded some areas to give "tooth" for the primer and paint. The areas which I scuffed but missed bead blasting peeled after a couple years. So I was planning on beadblasting these covers.

Paint: The Tempo crinkle paint, like your experience, worked well with 3-4 coats, barely flawed, ending with a heavy build-up.

Heat: In the case of my instrument panel - heat lamps were applied as soon as the paint layers were applied and flashed. The crinkle started showing up about 1/2 hour thereafter.

Mill Finish: I plan to let the crinkle paint harden for a week, check the hardness before sanding so as not to 'tear' the paint surface at the edges. I'll set up a trial run with sandpaper on a sanding block. I can always do it over if I don't like it.

Best,
- Art

 

Soda blasting works well. This took about 10 minutes. I missed a few bits, but most of the black you see is voids in the casting.

Also, you can see that some previous owner used a mill, but not very well - notice how the letters have lost definition and the oval next to the "I" has a section missing. Fortunately, my QP3 came with all-black cam covers, so I can swap without hurting the appearance of either car. The right intake cover is different, but the perpetrators of this crime somehow missed that one, so I can use the original.
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Also, you can see that some previous owner used a mill, but not very well - notice how the letters have lost definition and the oval next to the "I" has a section missing. Fortunately, my QP3 came with all-black cam covers, so I can swap without hurting the appearance of either car. The right intake cover is different, but the perpetrators of this crime somehow missed that one, so I can use the original.[/QUOTE]

Gentlemen,

The cleaning I did with a professional paint stripper. Degreasing with an engine degreaser and rinsing it of with hot water pressure cleaner.
The real trick lays in the pre -heating which I did with an electric 2000Watt heat gun.
After applying the 1st layerI carefully went over the fresh painted surface till it turnd matt. Repeat thi for 4 cross layers and keep applying hot air on the paint. By the tiem you think you goofed up the stuff starts to wrinkle. Let ift dry for a week o to and then do your finishing.

See attached pics.

Ciao,

Bart
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Bart,

Your Khamsin engine looks, as we know, fantastic.

You used a paintstripper, which I'd like to do as well to avoid damage to the sharp edges of the casting, but am reluctant for fear that it will attack the aluminium. What stripper did you use?

Best,

Jack.

 

Dag Jack,

Always interested in strippers, right?

I am affraid that the stuff is now prohibited due environmental legislation.
It is a Dutch brand called: NELF Wenflex Professional Paintstripper.
May be you can still get it in Joburg?

As you may have taken from my pictures I care about the environment and I have the greenest spray cabine of our neighbourhood....

Drove the K yesterday after changing the top ball joints / tie rod ends which had a little play, vertically!
Bought myself some new old stock which fortunately contained these ball joints with their rare M14x 1,25mm pitch.
She steers like a razor blade again!

Keep smiling,

Bart

 

Thanks Bart, I'll have a look in Cape Town
I'm getting my cylinder head back from the engineers next week, si I better get cracking at the cam-covers.

Btw, I don't get it that all these relatively small manufavturers had things like ball-joints and dizzy-caps etc. made proprietary to their cars. These onscure parts make it difficult and expensive to keep them going now, and they must have been a considerable expense at the time of manufacture as well. Beats me.

You're lucky with the mild winter there and therefor the absence of road-salt!

Enjoy,

Jack.

 

Wife texts me from her office yesterday afternoon..
"What shall we have for dinner?"

Me:
"Um…. how does baked aluminum DOHC valve covers with a drizzle of fresh wrinkle paint sound ?"


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Possibly a week on the couch if the oven stinks for a while ...

There's always baking soda though I've never tried it.

But enough of that minor stuff, how did they turn out?

 

They are doing great - but still "in progress". The oven fared well and retained no smell. I had let the paint dry for 4-5 days before baking and all I had to do was air out the house.

Yesterday I set up a table outside in the sun, and I used the suggestion to scrape the top layer of paint and primer with a razor edge - This is GREAT advice, THANK YOU! It took off 90% of the the thick, soft wrinkle paint very nicely so it won't gum up by sanding block.

Here is a pic of them enjoying some sunshine yesterday… (I will start sanding the next few days)..
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Just be sure to not back over them as they bake in the driveway ...

I forget, whose wrinkle paint did you use?

That looks like a zinc chromate primer underneath?

 

Yes, I used zinc chromate and wrinkle paint by Tempo, from Aircraft Spruce and Supply Co. I suspect this sheen is more glossy than 'concourse' correct..

I'm done with the sanding, I made a narrow block to limit the sanding between the mount bosses and raised lettering. Started carefully with 80 grit, then switched to 120 grit to give the finish just a little "grain"…

It's remarkable how different the castings are - the heights of raised lettering, the MASERATI lettering, the amount of voids, and the bosses on the far right cover are lowered as opposed to raised like the other three - all of them are slightly different.
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I all, this is an interesting read.
Does the unprotected, sanded finish corrode??
Cheers,
Richard

 

It loses it's gleam of course but unless you're in a highly corrosive environment it just dulls with a nice patina. You can always freshen it up again too.

 

Good question. Yes, I expect cast aluminum, no matter what the alloy is, will corrode to a dull powdery-grey-white surface if left to the ravages of the environment (e.g.: have you ever seen an aluminum carburetor left 10 years in a salvage yard?).

But with normal "use", the presence of oily engine vapors, and an occasional wipe down, that corrosion won't have a chance to build up, and it will remain shiny.

Aircraft aluminum is an alloy able to be protected by an alodine treatment.
Automotive trim is usually anodized.
Best,
- Art

 

Hey Art,
I see what you mean when in the environment on an engine.
What is alodine?
I work within the Aerospace industry and am aware of anodising and alocrome 1200 to meet the requirements of various industry standard requirements. Didn't thing that a clear brush alocrome could be used.
I see from your post you have a classic aircraft, what is it? (not really the place in this area in the forum I know but....)
Cheers,
Rich

 

that was ment to be "think".................

 

You really don't need to resort to an Alodine treatment for something this simple IMHO.
I did a couple of cars this way over 30 years ago and while they don't look like they did the day it was done it's still very acceptable looking to this day.

Now I used the Alodine when I restored the DCOEs on my Espada because I had to bead blast the bodies for corrosion removal and I knew that in my environment they would deteriorate quickly. That has worked out just fine too.

I haven't heard anyone definitively identify how Weber protected them originally.