Fellow 6packers: My 74 1/2 seems to have a vacuum problem that plagues me
periodically. I found my idle refusing to drop between shifts ...seems to
stay at about 2200, but then creep back down to 800 if I wait about five
seconds at stop, as at an intersection. I pulled off the tube to the vacuum
retard at the distributor and to my dismay found only a 150 to 200 rpm
increase. Before the problem the rpms jumped up about 500 (to 1300) until
the tube was reconnected. My troubles seemed to start after I cleaned and
hosed down the engine this weekend. I had a similar problem last month, but
it disappeared and the vacuum was maintained after I removed and cleaned all
of the emissions tubing. Could I have plugged up something with water or
gunk when I cleaned the engine? I am again going to take all the tubes off
and clean them, but I do have vacuum to and from the carbs...the problem area
seems to be no vacuum from the distributor to the several tubes on the
thermostatic switch on the radiator hose and to and from fuel traps. Could
the thermostatic switch be bad or the vacuum retard unit need replacement?
If the latter needs to be replaced, how is it removed from the distributor?
I don't see a nut or screw to loosen; the long end of it just seems to be
inserted into the distributor somehow. Bentley's manual does not seem to
explain how to remove it.
Also, another concern may be relevant here. I thought that I would
remove the EGR valve and inspect it, but I may have screwed up..I thought
that the screw on top of the valve was to be turned for removal of the valve.
I found it very difficult to turn, applied some rust penetrant, and finally
it would turn somewhat. I then saw that the valve unscrews from the manifold
(I think), and this small screw may not have anything to do with removal.
What does it do...some internal adjustment or does it help dismantle the
valve itself for cleaning? Did my tinkering with this somehow break something
inside the valve, causing my current vacuum problem? I hope I do not need a
new valve, as no supplier seems to sell one ....help guys? (I noted the
problem after cleaning the engine and then messing with the valve...started
car only after doing both. I then noticed the vacuum problem.) One final
thought..... I have slightly adjusted the by-pass valves on both carbs by
turning the screw a half turn or so w/o any affect on my idle, as the vacuum
problem does not allow for any idle change....can't follow the Moss catalog's
instructions as a result to reseat the valves. Thoughts guys on any of the
above? Bob Pierson