Has anyone painted aluminum heads before?  Or powder-coated them?  I'm trying to make my AFR heads look a little more restoration-quality.

If you haven't done it, don't ***  

I've never known anyone to powder coat a head, but I don't see a reason why it couldn't be done. As far as painting goes, it used to be pretty common (probably still is) amoung the sleeper crowd. I've known people who have gone as far as texturing the aluminum to look more like iron before painting them.  

I painted mine.  

Just make sure you get primer/sealer that is compatible with aluminum.  Most but not all modern epoxy primers are, but check with the paint folks to make sure.  I have heard of guys using extremely rough sand paper (32 grit?) and a rubber mallet or hammer to texture aluminum to look like a sand casting.  Good luck and be careful with the paint fumes they can be deadly!  

I should have sanded and primed mine, but I didn't. Just hit it with paint. 6 years later they still look good!  

Cool.  So, to summarize, plain-old VHT engine enamel paint will work, but sanding with primer coatings will work better?

I'm putting together something like a sleeper engine.  I'm making kevlar replica valve covers with the Chevrolet script.  In composites, Kevlar is like carbon fiber but a little less strong, a little more flexible, and easier to find at reasonable prices.

I'm making a four-stage kevlar dry-sump pan with interchangeable sucker thingies, too.  I love composites.

Anyway, I'm making this all as color/dimension correct as possible.  The Edelbrock Victor Jr. label and AFR labels are going to show through, but the orange paint should make them fit in a little better.

what would you possibly need kevlar valve covers for???!! let alone a kevlar oil pan?    how much of a sleeper can this thing possibly be and whats it in?   sounds cool though

Don't have a car.  I just like engines.  

Kevlar is just the economic choice for me.  I buy a ruined stamped steel part from some NASCAR or NHRA used parts dealer on eBay.  I plug up the holes with duct tape and make a positive or negative mold out with a tub of Crisco and some plaster of paris (from Hobby Lobby, Lowes, Home Depot, Michael's, etc. about $10/25lbs).  

Then, instead of beating the crap out of steel to flatten imperfections, I can take flat sanding device to make the mold flat as a sheet of glass.  I find it much easier to work with a plaster mold than metal pans.

If you paint it right, you get a hard, slick surface for the Kevlar to sit in (or sit on).  If you haven't worked with modern composites, I posted an article entitled “What I know about composites” in the general discussion.

If you used Crisco and common sense, you should end up with a nice Kevlar duplicate of your original part.  Kevlar is hideously light, resistive to abrasion, and just easier to manipulate than steel or aluminum sheet metal (for me).

I read your post on Composites, but I think you neglected one fact, Thermal Cycling.  It may or may not hold up to multiple hot/cold cycles, they might be strong and a bit flexible but that is pretty much assuming atmospheric temperatures.  From what I found on the internet it can withstand constant temperatures of 800*F, but the thermal cycling tests I found only cycled the temperatures up to 120*F. When an engine gets to 220* how does the kevlar hold up to heat and the vibration? I'd just hate to see an oil pan crack apart.  I see kevlar used as body and interior parts and yeah the stuff is tuff, but would it last on a daily driver?  

that sounds like a real cool father son project on a crappy rainy weekend! please post some pics when you finish it i would love to see how they turn out

No idea.  I know that solar-powered cars use kevlar for structural members that take a lot of punishment, but I doubt those parts take a lot of thermal bashing.

The first, not-that-exciting stages of my engine build can be seen at:

http://meweb.ecn.purdue.edu/~bmunden/projects/index.htm

Up to 200 Fahrenheit, higher curing temperatures correlate with higher service temperatures.  So if you bake your part at 200 while the epoxy cures, you should be good to go for heat cycling.  I think.  Still no research.

If you're trying to do this in your kitchen oven secretly, I think you might be able to use a big turkey cooking bag to get away with it.

Scientifically higher service temperatures do not necessarily mean better thermal cycling properties. The cycling stresses the material mechanically by expansion and contraction which is like bending a paper clip until it breaks. Sustained temperature is a different kind of stress, mostly chemical breaking of bonds. Good info though you have my curiosity, if only I knew a materials engineer.  

I'm taking a course in materials engineering, so I'll pay special attention to polymer behavior.

For what it's worth, I know that composites are being used for turbofans in some of GE's plane engines.  These don't see nearly as much heat as the compressor blades (especially not the turbine blades), but it's still a beam of hope.

On second thought, I'll probably just go up to my materials professor after class and ask him how to do it.  I have a hunch that an additive may be required, such as cavisil (itty bitty fluffy stupid-strong spider web structures that you mix into the epoxy).

>> Finally, for a post that's relevant to this thread:

>> I got my 195cc AFR Eliminator heads today.  It's going to be hard to convince myself to paint them Chevy orange.

Ah yes, I remember hearing that the fan blades are composites, and those do go through some temperature extremes. Super cold upper atmosphere to ambient temps.  So that sounds promising. Cool.