I have gotten a billion questions on what I am using for engine compartment paints...so I gathered some pictures and explained it on the Centurion forum. Here's a copy.
Don't take this as gospel, it's just what works for me. It's also an affordable alternative for the do-it-yourselfer.
I've found various off-the-shelf spray paints that are correct-appearing, in my adventures under the hoods of a the last few engine compartments I've ripped apart. Most of them are from Dupli-Color, and are high heat paints.
DE 1635 Ford Semi Gloss Black
The first one I seem to go through a case on every car, is semi-gloss black. I use this on all the black surrounding areas such as the firewall, wheel houses, and core support. All the black engine brackets are semigloss as well. There ARE a couple brackets that are not black. I will elaborate on this in a minute.
DE 1613 Gloss Black
Gloss black (high heat) is used on the air cleaner (yes, it is GLOSS black, nothing else.) I have also used this on the crank and water pump pulleys, but I thing they are supposed to be semigloss. Judges do not normally deduct points for things like this, called "over-restoration." It's up to you. I also paint the voltage regulator cover and the coil gloss black.
DH 1608 High Heat Red
This one should be obvious - the engine is painted this color. There are a few ways to get the engine painted. One way is to paint each part, and then bolt them on individually. If you are going for a factory correct look, this is the wrong procedure. You must assemble the entire engine first, and THEN paint it red. This also aids in sealing gaskets and small leaks that can seep out of poorly sealed gaskets. Engines were originally painted with the fuel pump and distributor already installed. SOme of you have noticed that there is red overspray on the vacuum advance can, and the fuel pump is red (at least the top is). This is CORRECT factory procedure. Most of us choose not to do this, due to the sloppy appearance. Judges will not deduct points for non-painted fuel pump and/or distributor. Once again, it's your call whether you want your gaskets to stand out, or to blend in with the rest of the motor.
DE 1636 Clear
This is an optional step. I choose to clearcoat all my bare metal parts, just to preserve the look, and protect them from rust. Most, if not all bolts that are left bare, are clearcoated. Keep in mind that I do not BATHE the parts in clear, I just lightly coat them for protection. All the relays, windshield wiper motor, and some other various knick-knack parts are cleared.
DE 1651 Cast Coat Iron
I recently discovered this one. This has many uses to me. Steering box, master cylinder, hood hinges, exhaust manifolds, and starter shield will all be this color. I also used this paint on the upper alternator bracket. This part is supposed to be grey phosphate plated, but the cast iron paint does a good job of emulating that plating. Same thing with the hood hinges - supposed to be grey phosphate.
Note in this picture the master cylinder and steering box. I used the Eastwood brush-on stuff here - the Duplicolor spray I noted above is a smidge darker than this...
Duplicolor EMC 202000 Yellow Anodized
Now, I'm getting into territory where you have a choice to make. Gold cad plating is of course the correct finish on some particular parts such as the power brake booster, choke coil, hood latch, and master cylinder lid. I've found a neat paint that does a good job emulating that gold cad plating. If you aren't interested in spending the bucks to send all these parts out for plating, then do this. You either need to media blast the parts first, or clean them up and put a clean coat of silver or aluminum paint on as a basecoat. After you have the basecoat on, DUST the part with the yellow anodizing paint. It builds fast, so be very sparing with the paint. If you screw up, dust some aluminum paint back on to even out the color. This will take a few tries to get it right, so be patient.
See the picture I posted above for the finished parts I "gold cad plated" using the method I decribed in the last paragraph. (master cylinder lid, brake booster, choke coil)
I don't have a paint code for this, but it's readily available. The only things I have used this for, are things like the healight bezels. The grille appears to have a semi-gloss black on it. I can't confirm the correct gloss on it, though. Most of the grilles I have seen on other cars have flat black on them, but both of my Centurions appear to have some sort of gloss in the grille black. The lower portions of the headlight bezels and grille are a light argent/silver color. ...a bit tough to get exactly correct. It can be fudged, and no one will see a difference as long as the grille matches the bezels.