Engine Paint

I am pulling the WT 400 motor out of my 67 GTO and I am going to repaint the engine. Do I need to remove the old paint or can I paint over it? If I need to remove the old paint how would I go about doing it? I don't have the finances for a shop to do it so it is going to be done "in house".
Thanks  

Woo boy- what a mess. Good question, I'll try.

First let me say that whether you do a pressure-wash it and fog it approach, or a museum quality job here, usage is giong to destroy your work over time.

Spraying a freshly built engine that has been cleaned in a hot tank and degreased is one thing, but refinishing a used one is quite another. Here is what I would recommend in your situation:

After removal of the exhaust manifolds, distributor,and carb,plugs, etc, and proper masking of their openings, go at it with the degreaser of your choice. I might use a strong citrus type degreaser or maybe gas. Using whatever you have at hand like a bristle or wire brush, and a scouring or scuff pad get everything that ain't paint off there. If using water it helps if its hot. To finish cleaning, use lacquer thinner and your scuff pad, then wipe dry with a rag. Do this only with adequate ventilation and don't light up.

Now that you can see whats there, use sandpaper (maybe 180 grit) by hand or whatever sander you may have to "feather out" any chipped areas where paint has flaked off. Just knock it back until the loose or chipped stuff is gone. Use your DA sander on tin like valve covers, oil pan. The scratch pattern won't show like it might if you hand sand the flat areas. Sand everything you can reach thoroughly.

At this point much of the old paint is gone, so as you see the answer to your question is "Somewhere in between."

Once again, after sanding, put on your safety glasses and crank up the compressor. Hit the whole thing very thoroughly then with maybe 409 or another strong water based degreaser. Blow off, let dry. Now is the time to do your final masking. One last time, clean with lots of rags and a good wax-and-grease remover or lacquer thinner. Wear latex gloves and have adequate ventilation. Wet with one rag, dry with another. If you want to go the extra mile, gently tack rag the open surfaces while gently blowing with air.

You are ready to paint. Do not use car exterior paint! Tempting for color match purposes, but engine paint is different! Use engine paint. No matter how grand your efforts, the engine will look repainted, the color won't be exact, and will always age faster than the factory paint did. But its definitely the right thing to do. All you have done here is give it a sporting chance, so take your "fresh" photos before that cross-country drive!

Wish I had a Goat-

Dad had new Tempests in '62 and '64. They brought me home as a baby in a new '66 Tempest Sprint6. They laid my noggin against the arrowhead on the door panel and it imprinted my skull, I think. That was my first car too. Dad said he looked at GTOs then but when he turned the key on one in the lot, it scared him! LOL  

I would not use gas to clean your engine I would use degreaser the industrial purple from home depot works great.
I would only remove the loose paint on the engine.  
professional hi-performance engine builder.
Horsepower sells engines and torque wins races

Thanks guys.
I am having a hard time find Dupli-color DE1616 from my local suppliers. Is Dupli-color the only brand to use? I would like to touch up the engine compartment. I looks like there is semi-gloss black in there right now. Can I get more semi-gloss for some touch ups or would I have to paint the whole compartment to get it to match?  

As far as the semigloss part...Sometimes you can spot spray places and blend it in a little by stepping each coat farther out. But for best appearance yes paint as much as you can so it will all match.

The blue metallic... Well I'd probably keep trying to special order it from a different parts store I guess. Doesn't look to be many choices. If your car is a weekender not a daily driver, and color correctness is important, go ahead and use exterior car paint (enamel) custom mixed. There used to be a lot more choices but DupliColor looks like the only one now. The preparation is the important part as far as making it last. The exterior paint will build up thicker and be shinier but it will yellow and flake faster.

Not much help there, sorry.  

The blue metallic is available at most auto parts stores where I live here in Houston Texas, but I've had a hard time finding the original non-metallic Pontiac blue. With my 400, painting over the old paint was not very succesful. Although I did everything I could to prep it, the engine still had flash rust from mosture and heat fairly soon. As idrivejunk emphasized, the preparation is the most important step - and making sure you are not spraying over built up crud.

Evidently, engine paint works best when it's heated up or "baked on" before completely drying. I never have figured out how to do that when the engine is out setting on an engine stand!!!  

For the metallic blue I use plasticoat brand.  
professional hi-performance engine builder.
Horsepower sells engines and torque wins races

For the best black under the hood Eastwood has the right stuff. And if you plan on using gas to clean your motor and hit it with a wire brush call 911 first so they can be circling the block. They'll hear you screaming and come on in.  

I was hoping the might and the maybe and the better choice listed would keep them from choosing gas, and that the safety warning would apply if they did. Flammable solvents are best at dissolving thick oily crud. Gas is just the most readily available.

So I stand corrected. I assumed a certain level of savvy and thats my mistake. A stiff nylon bristle brush would be the thing to use with gas, not a wire brush. Nobody said anything about the lacquer thinner being mentioned. It has a flash point of 11 degrees. Cute mental picture with the firemen circling the block though

Pman, do you buy that plastikote from a walk in parts store or order it with your speed parts?  

Iuse plastic-kote#227. Make sure you get you get engine enamel that resists heat to 500degrees. Go on line and google plastic-kote  . Then you can put in your zip code to find a store or auto parts that handles it. If not in stock on shelf they should be able to get it in a day or two.  

Never use gas to clean anything intended for paint-It is petroleum based-Use the purple cleaner from Castoroil-super clean  or Home Depot  The main thing is to try and scuff any surface to receive paint if possible Paint needs to be able to grab a surface --slick surfaces do not promote adhesion  

Hey Idrive! I forget what city you live in, but the plastikote is pretty common in Houston - they even have the metallic blue at most places like O'Reilly's and Pettagrew Smith (that may be just a local chain - not sure). I agree that it is a reliable brand of engine paint, and it has that better kind of spray nozzle that doesn't just "poot" out the paint.  peace  

I get the plastikote from a parts store.  
professional hi-performance engine builder.
Horsepower sells engines and torque wins races

I would use high heat primer first . The paint will last longer and won't peal ! Check out the thread in - Body/paint upgrade - called -Paint Stripping .  

Thanx, Pman

Brazil, I'm in NW AR  

High heat primer sounds like a good thing!