So, I did that, after making sure the point gap was set correctly.
Once the timing was set, I fiddled with the idle mixture and idle speed settings a few time before checking the timing again--it was still at 5 degrees before top dead center.
With the vacuum advance reconnected, the engine is now running better than it ever has before. On the test drive, it no longer bogged down at 45mph. I got it to 60mph and it felt like I could go faster, but I reduced the speed back to 50mph....that's fast enough for me in that truck! :-)
Oh, the vacuum chamber advances the timing as the vacuum increases. I made some measurements and dragged out my calculator and decided that at full vacuum, the vacuum advance can make the timing about 6 degrees more advanced. So, at idle, there is 11 degrees of timing advance.
: Hey Eric, I am having some difficulty getting
: my 170 in time as well, I bought a new
: remanufactured distributor i timed it with
: the vacuum advance hooked up but can't get
: it timed better than 10' off, can't remember
: if it's advanced or retarded. I'll have to
: try unhooking the vacuum. Did it work for
: --Previous Message--
: The vacuum advance on my FC-170 distributor
: developed a leak and quit moving. I found a
: used one that both moves and does not leak.
: The service book isn't terribly clear on
: setting the ignition timing with or without
: removing the vacuum line.
: Is the "standard method"--remove
: the vacuum line from the distributor, cap
: it, set the timing and reinstall the vacuum