OEM Exhaust Manfold

This week my new original-style exhaust manifold arrived! I bought the manifold on ebay after keeping an eye out for one for several months. The manifold that came with the car was an aftermarket header, which is pretty typical because the OEM version was prone to cracking.

This one actually does have some cracking and evidence of a repair. I will probably have to send it off for more repairs.

But for today I spent a little time cleaning up the manifold with water, Simple Green, and a brillo pad.

Exhaust Manifold Coating

Today I painted the exhaust manifold using a high temperature coating from Eastwood Company that is designed for exhaust components. This product is meant to have the appearance of new cast iron, which is the material the Datsun manifold is made from. My manifold had already been coated in a white material, so this should restore a more “stock” appearance.

Prior to painting I cleaned the manifold again using Simple Green to remove and dirt or grease on the surface.

The product I used is rated for up to 1200 degrees and cost about $15 for the can, which was enough to thoroughly coat this manifold.

I sprayed on one coat and then did a second coat after an hour.

Here is the final product. After the paint has dried somewhat the effect dulls to more of a cast iron appearance.

Exhaust–Out with the Old

Next I removed the exhaust from the frame. I had already detached the exhaust manifold when I removed the engine, so the only connections to the frame that remained were the exhaust hangers and the fact that the exhaust actually feeds through a hole in the crossmember of the frame. I don’t know if this is the original exhaust, but I don’t think it is because it is missing the distinctive “megaphone” tip. It is quite rusty, though, but that is fairly typical of an exhaust.

Here are a couple of pictures of the rear and mid-sections of the exhaust, where it runs up over the rear axle.

I began at the rear of the car, removing the nuts that held the brackets welded onto the exhaust to the frame’s exhaust hangers, which had rubber blocks to make them flexible. I removed the nuts using a 13 mm socket. There were two sets of hangers, one at the very back and one just in front of that one.

Moving towards the front of the car, the exhaust then feeds through a hole in the frame’s X-shaped crossmember. I removed the nut from the rear of a pair of straps of metal holding the pipe in place.

Then I used what is, in my experience, the single most useful tool for demolition work, my crowbar, to pry up the rear section of the metal strap and then the front section to expose the other nut.

I then removed the other bolt and pried up the strapping to free that section of the exhaust pipe.

Between the two pieces of the frame crossmember was a resonator that was clamped into place between the two straight pipes. I removed the clamps by loosening the nuts using the 13 mm socket.

With all the rust, however, I was unable to remove the pipes from the resonator. So I used what is, in my opinion, the second most useful tool in demolition, my reciprocating saw to cut the resonator out.

At the front, where the exhaust mounts into the manifold, there is another bracket on the frame. However, the exhaust was not connected to this bracket. This was probably to allow the engine to move a bit without tearing the exhaust free, as there was no section of flex-pipe.

With the resonator, which was clearly too wide to pull through the holes in the frame, cut out and all of the exhaust-mounting brackets disconnected from the pipes, I was able to pull the whole exhaust off the frame.

As you can see below, the existing exhaust had an external diameter of 1 3/4″. This 2-liter engine begs for more exhaust flow than that.

Manifolds

This afternoon I removed the intake and exhaust manifolds from the engine. Although it took some time, it was much easier given that the body is off the frame. Even so, some of the bolts were difficult to reach.

Mounted on the intake manifold are the carb spacer blocks and then the carburetors and the air filter assembly.

There were two hoses that feed engine coolant through the intake from right to left.

I removed both hoses by first loosening the hose clamps with a Philips head screwdriver. Also, on top the manifold is the bracket that the choke cable actuates to operate the carbs.

I freed the choke cable from this bracket by loosening the Philips head bolt that tightens the upper cable bracket and then loosening the lower bolt that holds the end of the cable. I used a 3/8″ socket on the lower bolt.

I then began removing the nuts that hold the intake manifold on the head-studs. I started with the middle and worked outwards using a 13 mm socket.

After I removed those four nuts the manifold didn’t want to come off, so I started removing the bolts for the exhaust manifold, not sure if there were some fasteners that held both manifolds in place.

I removed the top outside nuts using a 13 mm socket and the top inside nuts using a 13 mm ratcheting wrench because the choke bracket prevented me from getting a socket in there.

There were two lower nuts on the outside of the two inner exhaust runners. I was able to remove these using a 13 mm socket with a long extension.

Tucked-in just behind the outer exhaust runners were two more studs (one each side). The manifold prevented me from getting a socket in there to loosen those nuts, or even a ratcheting wrench over the end of the stud. I had to use a box-end 12 mm wrench to loosen the nuts, and it was slow-going.

But that completed the removal of the hardware connecting the intake and exhaust manifolds to the head. The exhaust manifold had three (at first I assumed there were just two, but there were three) bolts attaching it to the exhaust pipe. I removed each of these using a 14 mm wrench and a 14 mm socket with an appropriate extension.

Then I was able to work the intake manifold off the studs.

And next I pulled the exhaust manifold off.

I took both manifolds out to my stripping station. I then realized that the exhaust manifold is covered with some sort of high-heat coating that is bonded to the metal (it is made of steel while the intake manifold is aluminum). I will probably either leave it as-is or coat it with another high-heat coating because there are some voids in the finish. I did apply a coat of stripper to the intake, which appeared to have the same paint as the heat shield.

The intake manifold cleaned up nicely but will need another round of stripper to be fully clean. Note the shiny copper plugs on top of each side.

Once I’ve stripped the remaining paint the manifold will match the rebuilt carbs (once I rebuild them).

Heat Shield Paint Removal

This morning I spent some time stripping the paint off the intake heat shield. Both the heat shield and the intake manifold are covered in an off-white paint that I want to remove to give those pieces a more original appearance.

Paint stripper is toxic, so I set up a table covered in a garbage bag so I could dispose of the left-over stripper and the stripped paint easily. I cut the bottom and one edge of a large garbage bag and then just draped them over the plywood surface I had placed across two sawhorses. I wore safety glasses and gloves at all times when handling paint stripper. I bought a gallon of “aircraft stripper” by KleenStrip at Walmart for under $14.

I applied the stripper using a cheap 2″ paintbrush. It is best to apply the paste liberally but to apply it only in one direction rather than going over it more than once. That way the stripper seals to the paint and can go to work. Almost immediately the paint began to shrivel off the metal heat shield.

I allowed the stripper to work for 30 minutes and then returned to remove the paint using a plastic scraper. The paint came of very easily–this KleenStrip is good stuff. I also used a small brush with brass bristles to get into some of the crevices.

I’d like to get the heat shield plated in yellow zinc so it looks original again.