Type 2-4 Heater Box Manifold Installalation Tips
(Or Why Does My Van Backfire Every Time I Let Off The Gas)
by Bob Donalds

   This is a tech tip for the heater boxes on the type two engines with the copper exhaust gasket used to seal the exhaust pipe to the head. There is very little space to work up inside the head and the sealing can be a hit or miss prosess. This problem lead to broken studs from over tightening or worse broken exhaust stud boss. When I prep exhaust manifolds I start by filing the manifold gasket surface flat with a long file doing both surfaces at the same time. With any luck the gasket surfaces on the head for the copper gaskets is close to paralel. Next find a drill bit in your drill index that that fits in the exhaust stud opening in the manifolds and go up approximately two drill sizes then use this larger drill bit to open all 8 stud openings in both manifolds this gives you the chance to move the manifold around against the head. This allows you to get the flanges as flat as possible against the cooper gasket without the studs pulling the manifold in four directions at once. I also check the head to pipe clearance so the manifold does not hang up or bind at the stud bosses or the lip of the gasket surface. I have even gone so far as to take a file and shaped the flanges and manifold ends to get the job done. The gasket will leak and the engine will backfire unless the gasket makes a good even contact with the head and the manifold. When I am satisfied with the fit I use a exhaust paste on both sides of the cooper gaskets. Never use silicone to seal the exhaust pipes at the head it can not take the heat. Then while holding the manifold against the head I install flat washers and new nuts tighten the nuts evenly so as not to prelude the manifold to one side or the other. This can be hard to get right because the age of the parts. The manifolds must be sealed at the head first and then finesse the other pipes into place next.

As told to me by Gerg Malany of Gergs repair Natick Ma. Phone # 1 508 647 9749

~Boston Bob

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