What do you high detail guys do? I've heard primer isn't necessary and adds to paint thickness keeping heat in, but I've also heard color lays down much nicer on etch prime, bonds better and reduces fish eyes.

I use etching primer and then Nason single stage.

Mopar never used primer and neither do I on the block or heads. But I do use primer on the tin, like valve covers, timing cover, pan, etc. What kind of finish are you looking for? If you want better than factory appearance, a filler primer on the block and heads will smooth the rough castings somewhat. I have not had any adhesion problems without primer but I clean the rough cast several times with wax and grease remover and ScotchBrite pads until I feel there is as little oil and grease left as possible. That's where the fish eyes come from. And I use a good quality acrylic enamel with some flattening agent because I like a factory like finish. All of today's paint glosses better than the paint from the 60s and 70s, so it takes flattening agent to dull it down some.

That process helped my 71 GTX get OE Certified status at the Mopar Nats. And I have an engine that still looks good even thought I painted it over 10 years ago.

Ya my motors are way more shinny than originals and stays that way longer.

I wipe everything down with wax and grease remover to get as clean of surface as possible. I then use rustoleum industrial primer and rattle cans. Seems to hold up and not too shiney.

I'm looking for a better than factory look, but not crazy. I have the Roger Gibson street hemi paint with correct gloss. I also plan to get a factory look on the exhaust manifolds, but maybe just a dusting of orange as I think anything heavier would turn paint black.. Any advise here would be appreciated like paint manifolds separately? Tape off exhaust ports or just paint over? Use exhaust manifold gaskets but trim to get factory look since factory didn't use gaskets? Or install without gaskets?? Any other lessons learned?

I use what I use because I'm looking for durability. I drive my cars alot. The primer makes the paint last longer. The Nason withstands heat, gas and oil better than the rattle can stuff. My motors still look good years down the road. I'm not going for concourse correct, just bright, shinny and clean.

I don't like having paint under the exhaust gaskets so I either tape them off or I have a set of BB exhaust gaskets that I use,

Ever watch Graveyard Cars? Like the factory, they paint the engine assembled, manifolds, spark plugs and all. Only the porcelain on the plugs are masked more or less. The manifolds were pretty well painted all over. And if you watch Graveyard Cars when they fire them up, there is a lot of smoke and the paint for the most part disappears. It only goes black for a few minutes until it burns off. There is usually paint left on the nuts and the like, but most all the paint burns completely away on the manifolds themselves. So, I find it easier to just paint with the manifolds in place rather than go to the trouble of masking. And I use gaskets, but trim the excess as you suggested.

And on the intake manifold, if you block off the heat cross over, the paint stays good. If you don't plan to block the cross over, the paint will burn black there. We always block the cross over, especially given today's gasoline. If we're going for a more correct look, we burn the paint in that area with a torch to give it that burnt look.

It all just depends on the look that you are going for.

Oh, and don't forget to paint the timing cover before you install the water pump. It's not OE correct, but that way you don't have bare metal there.

I never have primered my engine everytime I have dissasembled and rebuilt or modified it and my car is a driver. Of course I have used specific engine enamel cans. And never have got paint being peeled off either

I find if you put down a thin coat of prime you can get the color to cover in one coat. If you have to put two coats of color on......you aren't gaining much and color costs a whole lot more than primer, eh?

color coats change with color used. Orange and red requires more than blue or turquoise

I use primer regardless of the look, Factory or Hot Rod style. The paint covers quicker with less coats. No thin spots at the casting lines and corners. For durability you can't beat urethane vs spray bomb. Fuel, brake clean, carb clean doesn't affect it. Clean the block with a prep sol type cleaner. Wipe with clean rags while still wet. Laquer thinner and brake clan dry to fast. They may leave residue that will cause peeling later. For you show guys don't be afraid to grind your castings smooth or use bondo to smooth things out. The only place we've ever had an issue with Bondo was the manifold side of BB valve covers . Stay away there. I have motors that have been bondoed running the same paint for over 25 years. They still look like new. This motor pictured was painted in 2004
Doug

Excellent advice from everyone. Dave - I suppose i should paint the valley tray (cross over blocked) and bottom of cast iron manifold too, right?

Looks good Doug. I do not plan on spray bombing, except maybe for self etch primer on tin parts.

Yup, primer - and I use the high-zinc etching-style stuff.
Those engines still look great 35-40 years on, longer than the factory's did.
No peeling or flaking, and more chip-resistant.

Oh, and yes, BB valley trays get painted, and I paint BB intake undersides too.

Given the way we treat our cars today vs the way they were treated when new and just cars......in my opinion, it is not a big deal whether you paint those blind areas or not. I personally do not. Where the paint gets between the pan and intake, it gets. And where it doesn't, it doesn't. You can't see the difference when looking at them. And I haven't experienced any other negatives.

But, if a guy wants to go to the time and trouble to prep, mask, and squirt the valley pan and bottom of the intake, then good on him. Although I feel it is a bit overkill, other than the extra work, there is no other down side.

As an example; I have a couple of late 70s motor home motors in the barn. Complete and original. And the valley pans are intact. I have seen valley pans rusted through, but they were exposed to the elements for extended length of time.

I've never primed if using engine paint. It only adds one more layer of paint to potentially make it peel or have other problems from heat.
If using normal paint using primer first is probably a good idea because most automotive paints weren't designed to go straight over bare metal.

What have you guys done for more extreme temp applications like manifolds, headers, or exhaust head pipes- comparable high heat prime or no prime?