I know the archives well cover gas milage issues, I've combed them. The
group has been most helpful for me to get my newly aquired 84 vanangon
running reasonably well. I have a mileage issue. I live in NW PA, so, there
are some serious hills around here. Im not counting on the 22 to better
mileage that I've seen in some of the posts. However, I can't seem to do
better than 12mpg.  And, it was worse!.  It has roughly 15000 miles on a new
set of heads, no leaks, good compression, new plugs, fair wires, new O2
sensor, Timed by ear, no misses. I'd like to put to the group where to start
to check, and in which order. I do have a leak at the overflow on the gas
tank, but I simply dont put in more than 10 gallons until I get to repairing
it. Its a plain old Vanangon, no camper, I pulled out the rear seats so
there is nothing in it but me and my two labradors. I dont have a lead foot,
and Im thrilled to note that I can crest the bigger hills around here easily
in 3rd gear at 40mph, so, power is fair.  It starts fine, idles fine, and
doesnt overheat. I Know Im missing something simple, Im thinking its either
the timing, although it sure runs and sounds fine from idle to 3500 rpm or
so, I hate to run past that, it gives me shivvers to hear that 20 year old
motor pushing that hard, or, its something to do with the leak at the
overflow. Oh, and an afterthought, new gaskets snugged tight on a good
exhaust system.