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. |