All you ever wanted to know about PCV valves and more...
The MKI & MKII valves are totally different. see link...
http://photo.starblvd.net/collector2/4-4-3.jpg
The MKI has a brass 900 angle adaptor which it screws into, and the
PCV hose has only one bend in it.
The MKII doesn't use an adaptor and the PCV hose has two bends (see
photo in link below) in it to make up for the difference. The MKI valve
can be taken apart for cleaning, the MKII can't. It is a lot cheaper to
make the MKII valve, probably why it was changed by Ford to the later
style.
Now what is odd is these valves were made by "AC" Spark Plug Division
General Motors Corporation. If you have an original valve the body will
be marked with the "AC" and Ford part number.
The MKI valve is marked: AC SPARK PLUG TYPE CV-643-C and C4ZE-6A666-AI.
The MKII valve is marked: AC SPARK PLUG TYPE CV-754C and C5AZ-6A-666-A.
Later replacements for the MKII valve are marked: AC ROCHESTER TYPE
CV-754-C & DOAE 6A666-A (note this is a 1970 Ford part number), the MKI
valve carried the same number and wasn't updated (it is now
discontinued). The "AC" part numbers remained the same.
Another odd thing is if you went to your Ford Dealer and ordered a
valve by the Ford part number you would receive a totally different
looking valve, I tried this about 15 years ago. The only "Tiger" valve
was sold by "AC". Why "AC" was selling valves with Ford part numbers is
strange. The MKII valve, 2 years ago, was still available from "AC"
aftermarket dealers, and still carried a Ford part number.
.
Additional info, if you haven't had enough. The PCV valves came in a box
with the "AC" aftermarket and General Motors part number, the same as
Ford does with Ford and Motorcraft parts.
The early MKI valves came with a little hard fiber ring/tag with the
part number "AC TYPE CV643C C4ZE-6A666-AI" printed on it, this was to go
between the valve and the angle fitting so a mechanic would re-order the
"AC" brand valve. If you look in the Rootes Tiger parts book you can see
this "tag" illustrated. Note the illustration of the MKII PCV and hose
is incorrect, they show it as being the same as a MKI (the MKII PCV hose
is shown in the photo link below). The brass angle fitting is a Ford
part, early valves came in "Autolite" bags, later they were Ford. Part
number is 378754 S, I believe these are now obsolete. There is no part
number on the brass fitting, it was probably made by a non-Ford vendor
and re-packed by Ford.
David Franchi
http://photo.starblvd.net/collector2/4-4-4.jpg
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