grumpyonetwo

A Question for all, at the moment i have the motor out of my 79, and the exhaust manifolds are looking old/rusty. i am thinking of getting them both sand blasted but i am stuck as to paint them after they are blasted or just leave them natural after blast ? your thoughts will be appreciated

trukatedave

Sounds like a personal preferance question. If you want all original no paint. If you want to dress up the engine bay find a high quality high temp exhaust paint. That should lead to a few "while I'm at its"...meaning paint for the block, valve covers, engine bay ect... What do you prefer?

1974ta

If you really want them to hold up I recommend Jet Hot Coating. I did my 70 with Jet Hot Coating.

They will rust VERY quickly without some type of coating.

I have heard of good results from hi temp cast blast paint that when cured looks a lot like an up painted natural manifold. Never tried it myself however.

Kind Regards,


Bill

Norm07

I did some research on the Cast Blast across several different forums and it appears to be a favourite. Paint it directly on the bare cast, then bake at about 400 Degrees for 4 hours. Not a problem if your wife shops for at least 5 hours. Seymour makes two types, you have to make sure you get the right one.....and it is not cheap, about $15 a can delivered.

Seymour Cast Blast , Cast Iron Gray High Temperature 1200 Degrees
# 16-2668

I am just getting ready to do mine.

Alan 71

Hi got,
This is an example of Cast Blast 1200.
The manifolds need to be scrupulously prepared...ABSOLUTELY rust free...for long lasting results.
Regards,
Alan

7T1vette

Seymour 'Cast Blast' cast-iron color paint comes in two heat levels; the highest one is for exhaust manifolds (#16-2668).

As mentioned, blast the manifolds, wipe them down with lacquer thinner, then paint two coats of Cast Blast on them. If you have an oven to bake them in...great! I do NOT recommend using the one in your kitchen. When this stuff bakes, it smokes and it stinks. The fumes are likely toxic.

But, you don't have to bake them in an oven. You can install them on the engine and reassemble to the car. As you drive the car, the heat of the exhaust will cure the paint to a ceramic coating that looks just like freshly cast iron. If you choose this route to cure the paint, leave your windows open and drive at 40 mph or higher. It will take about 4 hours of driving to get them fully cured. At first, there is concern because of the smoke and stink. But, it will fade and you will end up with good looking manifolds that STAY that way.

P.S. If there will be any time lag between blasting the manifolds and painting them, stick them in a plastic garbage bag IMMEDIATELY and seal the bag with duct tape. Bare cast iron takes only minutes to begin rusting. Get lacquer thinner (or other oil-free solvent) and paint ready so that you can 'do the deed' as soon as you open that bag.

Cast blast is less than $20; and it looks better than most other manifold paints AND the ceramic coating stuff.

grumpyonetwo

Thank you to everyone that replied, manifolds have been blasted and will be painted grey (cast iron grey) close to what Alan 71 has in his picture. then i will enjoy the driving time to cure the paint . Again thanks to all.

riverracer au

i bought this from a paint store local, bout 50$ for a small tin.



i blasted, painted normally, then dabbed the 2nd coat on with a stiff brush.



cured when the motor was installed and started, smoked and stank for a while.

gave them a quick makeover last august when i had motor rebuilt due to cracked heads.

7T1vette

It may be difficult to tell from a computer screen, but the manifolds in post #5 (Seymour Cast-Blast) looks much more like fresh cast iron than those in post #8 (no offense meant to the poster on #8). The post #8 manifolds will look like they have been painted, because that paint fills in the pores in the cast iron. Seymour Cast-Blast does NOT fill in the pores; and really savvy car dudes can't tell me whether my manifolds are 'original' (unpainted) or painted. They really do look like freshly cast iron.

grumpyonetwo

The paint you bought riverracer au is exactly what i used on my manifolds they got a coat today and another late tomorrow(thursday) and then a third on friday, bolt back onto motor on monday and hopefully motor back in on wednesday .

7T1vette

POR is good quality paint; and it is meant to use over 'well-adhered' rusty surfaces, so you only need to remove the loose rust when using it. Wire brushing would be the best way to get loose surface rust off the part. Blasting might not be good to do before using POR, as it WANTS the (adhered) rust, with which it bonds, to convert into an inert substance that acts as a 'primer' for it.

It should last a long, long time and will look much better than most manifolds seen in car shows.

Priya

I bought a pair of 2 & 1/2 inch manifolds from Iwamenowhesgone and they look surprisingly like new. I've had them for maybe a year (in the house) and they look rust free, would it be okay to paint them as they are?

7T1vette

Priya...

You should contact the seller and find out what coating is on them presently. Knowing that, you can better decide what should be put over it....if anything.

Now back to our 'regular' programming....

BBCorv70

How did you scrupulously prepare the manifold? Sandblast? Any other preparation?

PainfullySlow

There have been many great suggestions about a topcoat for your manifolds so I will not go into that.

I would strongly suggest that after you have the manifolds media blasted that you use a phosphate coating to absolutely ensure that no rust remains. Remember that these things can rust from the inside out so the interior should be done as well.

Eastwood also makes a coating specifically made for coating the interior of exhaust parts...I will see if I can dig it up.

BBCorv70

Any suggestions as to where to get the manifolds blasted, phosphate coated? I've never heard of iron manifolds rusting out but stranger things have happened...

7T1vette

Cast iron manifolds would have a hard time 'rusting out' unless they were submerged in salt water. (Can you say 'Katrina'?)

Usually, they will develop surface rust (very quickly!), and after many years may even develop enough rust for it to become 'flaky'.

Initial rusting will begin almost immediately after being blasted clean--unless you live in a desert area.

BBCorv70

Any suggestions where I may get the manifolds blasted, locally? Not sure I follow on the phosphate coating...

7T1vette

Use the web to find "sand blasting" or "shot blasting" sources in your area. Engine and/or transmission rebuild shops would have such cabinets. Some owner/operator mechanics would have them, also. It shouldn't cost much over $25-30 to get them blasted. But make sure you take them a clean trash bag to wrap them in when they get done with them.