Pontiac Headers Exhaust Manifolds - Tubular Entanglement!

To repair the portion of the header tube that was 0.226-inch out will require that material be added. To accomplish this, an oxygen/acetylene torch and a 3/32-inch pre-fluxed brass rod are used. A No. 3 welding tip with a "neutral flame" is established and the brass is slowly built up to close the gap. The goal is to build up just a bit of excess material, so the tube can be ground back to the correct size.

The header is allowed to cool and the template is put back in position. Since the brass had not completely filled in the missing material, additional brass had to be added. This time a No. 2 welding tip was employed to reduce the heat, so the brass that was originally added didn't melt and fall down the tube. Note how much brass was required to fill the gap.

Once the material is added, the brass that was built up has to be ground flat with the header flange. A 6-inch air grinder with a 24-grit pad quickly leveled out the brass braze.

The template was lined up again and checked to see how much material would need to be ground out for perfect port alignment. Notice the small amount of brass showing by both of Steve's thumb.

An air-grinder and carbide bit was used to remove the excess material and then blend the inner edge of the brass back to promote better flow. The process is done slowly and methodically, and each small change is reviewed against the template until it is perfectly aligned. Rather than continuing to repair the header's other three tubes, which would demonstrate the same procedures, the header is moved over to the TIG welding station and clamped in a vise.

A common procedure to strengthen the overall header and prevent a tube/flange junction leak due to header flex or corrosion is to weld a bead around that area. To prevent warping the flange when heat is applied, a junk head is used as a fixture to mount the exhaust header. Header bolts are installed on the rear header tube and the other ports will receive one bolt each to keep the header flat. The junction will be welded using a Miller Synchrowave 350 TIG welder. The 220-volt, three-phase welder is set to 200 amps and a 3/32-inch mild steel welding rod is used. Welding begins in a counter-clockwise manner, with the junction closest to the outside header bolt being done first.

Welding continues around the header until the inner-bolt is approached, which is too close to the tube to complete a weld, so it is momentarily removed. After completion, the bolt is put back in and the welding continues until there is a nice bead around the entire tube.

Normally, all pipes would be TIG welded in a similar manner, the header would be sandblasted, and high-temp paint would be applied to protect the metal. However, we demonstrated the process on a single tube, as this pair of headers would require an impractical amount work to repair and strengthen when compared to simply replacing them with a different set.

A cylinder-head slice is used to demonstrate a center-port alignment issue. Note the metal being scribed on the center port. Although it isn't visible in this shot, if the center runners' divider is aligned improperly, it is very common to have to grind the excess material off of one side and then braze brass onto the opposing side to "relocate" the divider into the center of the exhaust-port opening. The procedure to grind and braze is identical to what was demonstrated. The most common alignment problem with headers is the center port!