1979 Ford 370 - Ignition fails when engine hot
So, my 1979 Ford Carpenter B600 379 CI short-bus has an interesting intermittent problem. The Ignition seems to fail when the engine gets over a certain temp.
2 Years ago on it's maiden voyage (for me) it stalled 3 times on a 700 mile trip. Symptoms were as follows:
1) Engine lost power....unless I eased off the gas, it would stall.
2) When I pulled over the engine would idle okay for a bit, but if I tried to put it in gear and put any load on it, engine would stall.
3) Once stalled, starter would work, but engine would not catch. Sometimes turning the key got nothing (no click).
Got towed 3 times that trip. After first tow, Mechanic #1 thought it was clogged fuel filter. We changed the filter and bus worked fine (however, we neglected to consider that bus was now COOL after a few hours of not running).
After second tow 100 miles later, Mechanic #2 followed first mechanic's lead and we changed fuel filter again and added some seafoam to the tank. Again, bus seemed to work fine and we continued on our way
3rd tow was back to Mechanic #2 and he was bound and determined to figure it out. Carb was getting gas so we now looked at ignition. Put in new coil, everything seemed to work fine. Again we went on our way.
When the engine stalled one additional time I looked closely at the ignition and noted the cap that holds the wires onto the coil was missing and the ignition wires were lose. I adjusted with my pliers so they were tight and didn't have any problems on the return trip.
Last week I went on a trip to the same camping spot and on the way there, just past the same place we first broke down, the bus stalled again. This time I noted that the engine was fairly hot at the time and realized that every time the bus had stalled on the previous trip, it had been after I had either gone up a particularly steep grade or had been driving at fairly higher than normal rpm and the engine was likely running a bit hotter than usual. Usually the temp gauge lives with the arrow around straight up in the 12 noon position. When the ignition failed it was over about 2PM position...not in the red, but gettign close.
So, we let the engine cool down, adjusted the path of the ignition lead wires so they were not as close to the engine and once cool, she started right up. For the rest of the trip I made sure that I went easy on the engine and kept the temp down and we didn't have any more problems.
What I have so far is = when the engine gets hot, the ignition seems to fail. I've moved the ignition wires so they are not right on top of the engine. I've also noted that there is no radiator shroud...not sure if this would make enough difference in the heat for the ignition to fail.
Any other thoughts or suggestions? I want to try to nail this down and address before my next road trip in a few months...