Tuned-up and a bad case of gas
Once we had brakes, the "Go Devil" L-134 engine back together, and a new battery, it is was time for some test driving. Barry remembered being able to lope the old '46 along in low-low at barely more than an idle, but the '47 would stall with any load or even when accelerating to go up a slight grade. Master mechanic PD took a test spin in the meadow and commented that "it sounds like it is missing on one cylinder." A basic tune-up was in order.
We installed a new distributor cap, rotor, plug wires, and another new set of plugs. Even though we had just installed new plugs (you will remember what it took to get the old ones out) we noticed carbon build-up on the tips and the chief mechanics thought perhaps a hotter plug might solve the problem.
The chief mechanics still thought it sounded like it was missing, so next came a new set of points and an adjustment to the timing using the chief mechanics' ears for a well running engine.
All the basic tune-up work seemed to make no difference with the stalling when accelerating. A general discussion among the chiefs and other mechanics determined it was a fuel problem, most likely a bad accelerator pump. A search of the Willys Tech group turned up a note on a quick and simple test. The carburetor passed with flying colors, so the problem had to be elsewhere.
The Jeep still hasn't been driven all that much, so one working theory was that there might be a little water in the gas. A fill-up with premium grade and a little gas-additive also seemed to help with the stalling. There was no eureka moments, but all the small changes dramatically improved the engines performance and now the '47 passes Barry's low-low lope test.
We'd always known we'd needed to install a new muffler and tailpipe, but a significant back-fire during the tune-up process blew the remainder of the original muffler to pieces and left no doubt the exhaust system needed some attention. The Newgren implement lift we'd purchased mounts under the rear cargo area and requires the exhaust system be rerouted and the muffler and tailpipe be moved from out the passenger side rear quarter panel to behind the drivers side rear wheel.
The 1947 instructions for mounting the lift include details on moving the exhaust. The diagram at the end of the instructions is somewhat misleading and Barry spend a few hours of moving parts around trying to make it work. The first picture on the A Day with a Farm Jeep site clearly shows the exhaust exiting at the driver side rear. Using this evidence and ignoring the instruction drawings, Barry was able to replace and move the muffler, use part of the existing pipe that was curved to fit over the rear axle and attach the tail piece so that the exhaust now exits the drivers side rear. There appear to be an inordinate number of muffler clamps involved, but it works!
I am still amazed at how important sound is in working with these old motors. Both grandfathers would confess to hearing loss, but both also could hear engine misfires when it sounded fine to me and detect even subtle changes when doing the timing. I've used my dad several times to help me set the timing on my old tractors and my CJ-7. Using a timing light and specs doesn't always work well on old motors. There is enough wear and tear that requires compensation and that is where experience and good ears makes the difference.