No, the old Burb was 2WD- - - -and the last time I drove that road was in the late 1970's when it was just a set of ruts between some big rocks. Getting in there was fun! In the early spring just after ice-out those fish were so hungry they would bite anything I threw at them. I carried a 12 foot aluminum boat on a set of cartop racks- - - -no trailer needed!
The vacuum advance is only there for fuel economy at light throttle cruise. As soon as a little load goes on the engine like passing or pulling a hill, the vacuum advance goes away. What you need to check is the centrifugal advance- - - -a set of springs and weights under the breaker plate where the points are. Lift the distributor cap off and grab the rotor. Twist it clockwise. The tip of the rotor should move 1/4" or a little more, and then snap back smoothly when you release the pressure on the rotor. If it doesn't, you'll need to pull the distributor out and dismantle it to clean up and re-lube the weights and springs.
Once you're sure the advance system is working, here's a way to check for over-rich mixture. Install a ball valve in the intake manifold fitting below the carburetor where the windshield wiper hose is attached, and rig up a push/pull cable inside the cab so you can open and close it while driving. When the engine starts to bog down, pull the cable a little at a time to create a small vacuum leak. If the engine is actually running too rich, leaking a little air into the manifold will lean out the mixture and increase the performance.
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Jerry
