This is the intake manifold assembly for the 54/55 2-ton (Z-series 350 model) 270 engine. The upper piece is the intake manifold. The lower, rear piece is the exhaust manifold (that dumps to the exhaust pipe at the rear of the manifold. The piece that is attached to both manifolds is what I call the carburetor "heater box". The updraft carburetor attaches to the bottom of the heater box.
[Click here to open image in new window]

The heater box is on the right it is still bolted to the intake manifold (above) and the exhaust manifold (behind to the left). The heater box has a "venturi" between the carb and the intake manifold. Around the venturi are passages for exhaust gases surround and heat the "venturi". This serves to heat the fuel which cools during vaporization due to "latent heat of evaporation" (evaporative cooling due to vaporization of the fuel). On a conventional 1954/55 270 manifold assembly, there would be an exhaust damper inside the exhaust manifold that directs heated gases to the bottom of the intake manifold (for a downdraft carburetor). Observe the crack at the upper left of the heater box.
[Click here to open image in new window]

This is a close-up of the same crack as shown in previous photo. The assembly is still together. The cracked piece on the upper left is actually a piece of the casting that is entirely broken off.
[Click here to open image in new window]

The is a photo of the same "crack" from the rear side of the heater box.
[Click here to open image in new window]

This shows the broken piece in place. The lower left of the box is the surface that mounts to the opening in the exhaust manifold.
[Click here to open image in new window]

After removing the intake manifold from above the heater box, the cracked piece dropped off - had been complete broken, most likely due to the fact that someone (me) did not think about having the intake/exhaust ports side of the assembly planed and trued. (the exhaust manifold still connected to the exhaust manifold to the rear)
[Click here to open image in new window]

There is also a small crack on the other side of the heater box, The crack trails up to the left, and the extent of the crack is marked in the next photo.
[Click here to open image in new window]

The crack shown in the previous photo runs right to the top of the heater box,
[Click here to open image in new window]

Top view of the heater box. This surface mates with the intake manifold (above the heater box). The carburetor "venturi" is in the center.
[Click here to open image in new window]

This photo shows the first part of the preparation of the part for spray-welding. Mike Aldrich ground away material in a few mating locations of two p[ieces (middle bottom, in this photo). This would allow Mike to "tack weld" the pieces in the correct orientation and then continue to prep and weld other places in the mating surfaces of the broken pieces.
[Click here to open image in new window]

Another mating spot for the first "tack welds" to hold the pieces in the correct surface orientation.
[Click here to open image in new window]

This is the spray welding kit that Mike uses. It is sold by http://www.cwtindustries.com/spraywelders.htm Here is a discussion of this technique (and other welding techniques) http://www.aa1car.com/library/ar497c.htm "A standard oxy-acetylene torch, with the powder fed into the flame from an attached hopper. Typically used for glass moulds, smaller parts and repairs. Particularly suited for the repair of cast iron and machined parts. Powder welding results in a smooth, dense coating with a diffusion bond to the base material."
[Click here to open image in new window]

The first spray weld is complete. The exterior edges are not solid welds and will be ground away. The center of the weld-site is a solid .
[Click here to open image in new window]

The first "tack weld" on this end is cleaned-up (ground using a die-grinder and a carbide bit), and, another part of a new portion of the mating surface is grooved for the next "tack".
[Click here to open image in new window]

There is wasted powder on the work surface because our borrowed oxy-acetylene torch had an oxygen valve that could not be adjusted below 40 psi. I think that Mike said that 5-10 psi on the oxygen delivers the appropriate flow of powder.
[Click here to open image in new window]

After the broken piece was tacked into place, Mike then successively cleaned the previous wweld/welds, grooved a little further into new territory, and then welded. This was done repeatedly, until the weld progressed beyond the broken mating area.
[Click here to open image in new window]

This location is prepped for what will most likely be the last weld in this area.
[Click here to open image in new window]

This location is now ready for what will most likely be the last weld in this area.
[Click here to open image in new window]

A carbide gril and a die-grinder is used to groove the mating surfaces.
[Click here to open image in new window]

This side of the broken piece is ready for final aethestic (appearance-only) grinding.
[Click here to open image in new window]

This piece is good-to-go. Mike filed the manifold mating surface to be sure the weld was solid.
[Click here to open image in new window]

This mating area is now solid.
[Click here to open image in new window]

Another mating surface that is now solid and good-to-go.
[Click here to open image in new window]

The large crack on this side of the heater box is cleaned and grooved and ready for successive welds, cleaning/grinding, and re-grooving.
[Click here to open image in new window]