Late fifties(?) model starts up easily, runs smoothly for just about exactly an hour, and then starts to misfire (according to mechanics, it is not technically "misfiring", so i will call it "hiccuping".). The engine will be running, it feels smooth, exhaust sounds great, and then I will feel the engine hiccup and at the same time, I'll hear a single, slightly different burbly note from the dry exhaust. It will run fine for a few minutes and then hiccup again. The frequency of these hiccups increases gradually until it is simply running rough and the exhaust is an irregular burble and sputter. It will stall at the one hour mark, +-10 min.
If i let it sit for 20 min, the engine will start up again and run for about 15 min before eventually stalling the same way.
Engine temperature never goes above 170.
Oil pressure around 20.
Coil (and when it had one, the external ballast resistor) very hot, but according to infrared thermometer, within spec.
Engine was possibly/probably originally running on 6v system.
What has been tried so far:
Mounted external ballast resistor on aluminum bracket for improved cooling. No improvement.
Fuel was originally gravity-fed. Installed fuel pump, regulator and gauge, fuel return line and also removed fan that was apparently meant to cool the coil. Tried several different coils, some with external, others internal resistors. Replaced Pertronics Ignitor, all spark plug leads, plugs. Swapped back over to points ignition (which was found on boat, along with at least four coils, two resistors and a tangle of spark plug leads. These items, along with the fan aiming cooler air at the coil in the engine compartment, suggest to me someone has been chasing down an electrical solution to the engine's poor performance...). Put Pertronics back in, and engine ran worse than ever.
Just installed brand new updraft carburetor. Engine ran great for 30 min, then started it's usual decline ending in a stall at the one hour mark.
Side note, but it might be useful:
Just installed 100w solar panel with charge controller. Lights were indicating it was charging normally when I had the engine running (poorly) at low rpms. Thought I'd see if it would change at higher revs, of course it didn't, but soon noticed the solar charger control panel had gone dark and would not come back to life.
Help wanted! Thanks.
If i let it sit for 20 min, the engine will start up again and run for about 15 min before eventually stalling the same way.
Engine temperature never goes above 170.
Oil pressure around 20.
Coil (and when it had one, the external ballast resistor) very hot, but according to infrared thermometer, within spec.
Engine was possibly/probably originally running on 6v system.
What has been tried so far:
Mounted external ballast resistor on aluminum bracket for improved cooling. No improvement.
Fuel was originally gravity-fed. Installed fuel pump, regulator and gauge, fuel return line and also removed fan that was apparently meant to cool the coil. Tried several different coils, some with external, others internal resistors. Replaced Pertronics Ignitor, all spark plug leads, plugs. Swapped back over to points ignition (which was found on boat, along with at least four coils, two resistors and a tangle of spark plug leads. These items, along with the fan aiming cooler air at the coil in the engine compartment, suggest to me someone has been chasing down an electrical solution to the engine's poor performance...). Put Pertronics back in, and engine ran worse than ever.
Just installed brand new updraft carburetor. Engine ran great for 30 min, then started it's usual decline ending in a stall at the one hour mark.
Side note, but it might be useful:
Just installed 100w solar panel with charge controller. Lights were indicating it was charging normally when I had the engine running (poorly) at low rpms. Thought I'd see if it would change at higher revs, of course it didn't, but soon noticed the solar charger control panel had gone dark and would not come back to life.
Help wanted! Thanks.