: I just had my intake and exhaust manifolds
: ground. When I got them back, I laid a
: straight edge on the mounting surface, and
: it didn't look all that flat. How flat
: should it be - what is the largest deviation
: that I should accept? I had them ground
: seperately. Should they have been bolted
: together during the grinding?

: I just had my intake and exhaust manifolds
: ground. When I got them back, I laid a
: straight edge on the mounting surface, and
: it didn't look all that flat. How flat
: should it be - what is the largest deviation
: that I should accept? I had them ground
: seperately. Should they have been bolted
: together during the grinding?

: Surfacing them as a set saves you some time. I
: have done them seperatly and sometimes find
: that the 3 connecting bolt holes do not
: allow for the movement to get both surfaces
: on the same level. When I see this, I
: drill-out the holes in the intake to get the
: needed movement.
:
: Use the head as a guide, install both manifolds
: to the head with no gasket and with the 3
: connecting bolts and that gasket in place.
: Make contact but leave these 3 connecting
: bolds loose. Install the manifold to head
: washers / nuts and tighten to align
: manifolds to the head surface, then tighten
: the center 3 bolts.
:
: If the exhaust manifold is worped, you will
: need to adjust by grinding / filing flat the
: surface where the intake and exhaust
: manifold make contact. (heat riser area)
: Badly worped exhaust manifolds can never be
: adjusted and ground enough to make a good
: seal so it is better to find a replacement.
: (worped ones work fine when I cut them in
: half and make Duals out of them!)
: Surfacing the manifolds as a set will show you
: how badly they are worped and out of
: alignment.
: DD

: Thanks for the input. I'll try what you said
: and see if it helps. I still have the
: question of how flat the surface that mounts
: to the head needs to be - how much
: out-of-plane displacement can the manifold
: gasket take up?

: If you are still curious, my 1966 shop manual
: says: Test mating surfaces of manifolds for
: parallelism with a straightedge. Surfaces
: should be flat within .008 inch. Hope this
: helps.