A
fan shroud is essential to pull the maximum amount of
cold air THROUGH the radiator (not around it).
Information applies to USA cars, other countries may
vary. For example in most other countries the early style
fan/radiator/alternator/waterpump etc were retained
through 1970.
There
are a few variations on fan shrouds. The shrouds and
their matching radiators have various bolt patterns and
the bolt pattern can be in a different position relative
to the center of the radiator (LHD RHD) A lot of cars
have had the radiators switched. The earlier shrouds are
sized for the smaller diameter two piece 4-blade metal
fan or aftermarket fans the same diameter. The later
shrouds are sized to fit the 7-blade plastic fan or the
4-blade plastic fan conversion.
Basically
there are two early bolt patterns and one late pattern.
Figures are approximate center to center distances of the
holes in the shroud. Later shrouds (68-70) have slotted
holes so the horizontal distance varies a skosh. Many
people have modified the more economical Early "B" type
65-67 1/2 1600 shroud to work on 65-67 1/2 cars that
originally had the Early "A" type shroud. We used to use
the cheaper one in all kinds of applications to save a
buck, whether it was slotting holes or adapting an extra
bracket, it always was a great savings over one of the
more expensive versions. It will only work on 1600's
using the original 2 pc metal fan; or one having the same
diameter. The later plastic fan cars can not use this
shroud.
However
it ends up being mounted, you have to ensure that the
shroud ends up positioned on the radiator so that the fan
has clearance all the way around, by making new holes, or
slotting the existing ones.
"Depth"
refers to how tall the shroud is when you lay it on its
"back" on a table and measure the the
"height".
"Vertical"
and "Horizontal" refers to the center to center distance
of the mounting holes.