C2 EXHAUST MANIFOLD RESTORATION

[Rob A.]

I would like my exhaust manifolds to look as close to original as possible. I am planning to glassbead them. Is there a better media to use that will produce an original looking finish? They are a dark cast gray color currently, with no rust, so I assume they were painted some type of hi-temp paint in previous years. I realize they were painted along with the engine, but as long as they are off the car I though I would restore them.

[kenrobb]

Re: C2 EXHAUST MANIFOLD RESTORATION

Many years ago I did my 65 manifolds. I used a fine sand to sandblast them lightly. Then I applied "OSPHO", a phosphoric acid rust treatment. There are several other brands of this same treatment. This turns the remaining rust in the pits to a phosphoric oxide which is sort of black in color. Use it lightly as a little goes a long way. Wipe off any excess. I then used a VHT brand very high temp satin clear on them. This must be heat cured to dry. It can be done on the engine by running it or in your kitchen oven if you have the nerve! It has lasted many years of indoor storage. Looks just like natural finish when you apply a bit of engine orange around the flanges to engine and burn it in. This treatment does not look like it has been "painted".

[Mike M.]

Check This Option out

Hi Rob, A couple options, there are manys ways to do this,

http://www.z28camaro.com/restosvcs.html#manifold

Or there is http://www.techlinecoatings.com
I've used both, techline cast gray works good and its easy. Jerry at z28 is great also they will never rust, but they still must be coated with a cast paint to look correct. Mike

http://www.z28camaro.com/restosvcs.html#manifold

[Rob A.]

Re: Check This Option out

Actually, although I would like them to look new again initially, I want to let them weather as they did originally. Thanks for the suggestions...by the way I did use Jerry to restore my aluminum intake and was quite pleased.

[Tracy C.]

Don't forget to resurface the head mating surface

while you have these off.

I've found a pretty cost effective way to do this without taking them to the machine shop. If you have access to a surface table this is an absolute cake walk. If not, you need to devise a reasonable substitute. (more on this later)

Boogie down to the local Lowes or Home Depot and buy some 3" wide by 18" long sanding belts (used on your hand held belt sander) I usually get 4 each of 60 and 120 grit and a can of spray adhesive.

Bring them home and cut the belts across the taped seam joint so they can be layed out flat. Spray the adhesive on surface table (or flat surface) and place the paper down and hold in place for a couple seconds. Butt another one on the end so you have a 3" wide by 36" long landing strip to work on.

Exhaust manifolds are relatively soft cast iron and will sand without a huge amount of effort. Rub the inlet port surface (head mate side) back and forth, back and forth, back forth.....until the surface is all cleaned up and flat using the 60 grit paper. Repeat for manifold #2 and change the paper out to the 120 grit to smooth up the sanding marks.

These babies will fit your heads like the General did it.

Now if your like me and do not have a handy dandy surface table. While your in at Lowes, go back to the ceramic tile department and get some 1/2" X 4" X 36" stone back splash tiles (the ones with one smooth glazed surface) I bought 2 in case I broke one (I didn't) And find a good strait board to use as a foundation to mount the tile on to use as the "surface table" in the instructions above.

I've done several manifolds using this method...beats shelling bucks out to machine shop thug who may not really care that your manifold with "pristine casting numbers" is really valuable enough to the get extra care it deserves.

good luck,
tc

[Rob A.]

Re: Don't forget to resurface the head mating surf

Do you resurface the manifolds so that they can be installed without gasgets. I plan to install the manifolds as they were originally, without gasgets. That being the case, it's probably a good idea to resurface them as you say.

[Mike M.]

A Gret Job Also

Rob, Jerry did my intake, exhaust manifolds, and valve covers. My valve covers had the casting flaw in them which shouldn't be there for a 65. He removed it also. Everything came back excellent and very fast service. Mike

[Tracy C.]

The thing about this trick is that you can do it

at home, whenever you have the manifolds off.

I don't use gaskets, none required if the manifold fits flush to the head.

tc

[Clare Carpenter]

Re: A Gret Job Also

One of my exhaust manifolds had a crack that required bronzing. To cover the repair I had them Jet Hot coated "cast iron" grey. The color is too light of a grey to look like cast iron. Jet Hot also affects the porosity in the surface. Although they look good, they DON'T look original. Jerry @ Z28 did my intake manifold and I was happy with his work. I am thinking about having him try to do my exhaust manifolds but the spray weld technique he uses might not work well to conceal the bronzed repair. I had my manifold repaired BEFORE they made the reproduction manifolds.

[John H.]

Re: A Gret Job Also

Here's what a set of '69 Z/28 cast iron exhaust manifolds look like after Jerry's molten aluminum plasma spray re-skin and Seymour 1200-degree Hi-Temp Cast-Blast treatment; these have about 1,000 miles on them since the treatment, and Jerry says they'll stay that way. The .005" molten aluminum coating leaves the surface detail intact, but forms a permanent barrier against rust.

[Rob A.]

Re: Don't forget to resurface the head mating surf

I didn't have the head surfaces machined. They are already on the engine. That being the case will this method of resurfacing the manifolds so they will seal without gasgets still work? Is there any sealer that can withstand the temperature I can use, or will that just make it harder for the surfaces to mate. I really don't want to use gasgets.

[Tracy C.]

Re: Don't forget to resurface the head mating surf

Rob,

Typically the head surface doesn't require machine work to true up the exhaust port surface. The Head is healthy enough, it doesn't warp (unless the engine has been extremely overheated)

Exhaust manifolds however do tend to warp some with normal use. Not as much mass to them.

This method is as good as any to resurface and true the manifolds back up to "as new" flatness across the head mating surface.

I would not recommend any sealer or gaskets at all. Really, they are not needed! If you plan to have the car judged, sealer or gaskets will also cause a deduction.

tc

[Rob A.]

Re: Don't forget to resurface the head mating surf

Tracy,

Took the manifold to a couple of machine shops and wasn't happy with what they had in mind, let alone the price. Also wasn't happy when they went to grab my natural, clean, original looking manifolds with grease covered gloves. I Used your method using a piece of glass on top of the thick glass of my dining room table. Couldn't find 60 grade, so I used 80 to start with (a little more work). It appears to have worked very well. Thanks

[Tracy C.]

Ah..the ole resurface the manifold on the dining

room table trick!!

You are a TRUE CORVETTE GUY!! I'll show this to my wife, just so she knows I'm not the only person in the hobby that thinks like I do.

Glad it worked out!
tc

[Zachary K.]

Re: A Gret Job Also

I found Jerry's web site a few years back and put this maniflod process on a back burner. I am very interested in knowing how manifolds that have gone through this process would be scored. I think manifolds receive 30 points, 15 originality, 15 condition. Any ideas?

I must say, they do look good in your picture, John.