My tractor is a 1948 Ford 8n, serial number 64,520. It has a front mounted distributor and has been converted to a 12-volt system long ago. Last fall I was using it as I normally do to brush hog a pasture. It started to backfire and run poorly. I let it cool off a bit, and then it seemed to run fine, but the problem would be intermittent and come and go. I parked it for the winter, and I am now in need of it again.
If I acquire 30 hours of run time per year that would be a lot. In 2020 I had replaced the Ballast Resistor, Distributor Cap, Rotor, Coil, Points & Condenser, Plugs and wires.
I started using it this spring and it was running fine, but after a few uses (maybe 3 hours of run time this year) it started acting up again with the misfire and backfiring. I dragged it back to the barn and started troubleshooting. Here is what I have checked so far:
I appreciate all the folks that contribute to this forum and help many of us out. I look forward to hearing some other things I can go and check. Thank you for taking the time to read my post and respond.
If I acquire 30 hours of run time per year that would be a lot. In 2020 I had replaced the Ballast Resistor, Distributor Cap, Rotor, Coil, Points & Condenser, Plugs and wires.
I started using it this spring and it was running fine, but after a few uses (maybe 3 hours of run time this year) it started acting up again with the misfire and backfiring. I dragged it back to the barn and started troubleshooting. Here is what I have checked so far:
- Drained the gas and discarded. Removed the sediment bowl to see if the filter screen was blocked. It was not. Cleaned the sediment bowl and reinstalled. Filled with fresh gasoline. This did not change the way the tractor ran.
- Labeled my plug wires at the distributor cap end so I do not mistakenly plug them into the wrong hole. Although this would be difficult to do because the top plug wire would really need to stretch to get into the bottom hole, I still wanted to label them.
- Removed the distributor and verified the breaker point gap was set at 0.015”.
- Re-installed the distributor and problem was still there. Next, I ran a jumper cable from the battery to the coil to jump out any potential electrical problems in the wiring system. The tractor ran the same way, this had no effect the way the tractor was running.
- As a check, I removed each plug and connected to it’s plug wire and cranked the engine over to verify there was good spark. I did this for each cylinder and all four were sparking good.
- Just for good measure I replaced the spark plugs using Autolite AL-437 plugs gapped to 0.025”. This did not help the problem.
- Thinking perhaps there was a stuck valve, I removed the exhaust/intake manifold and shined a light inside each port while cranking over the engine. All valves were moving up and down. However, I realize a valve may not be fully seating and could be causing this problem. I have not done a compression check yet, but plan to do so.
- I removed the carburetor and thoroughly cleaned it. I verified all the jets had the proper settings. Reassembled and it also did not help.
- I tried running it without the air breather tube connected suspecting a lack of air flow. This did help.
- I check my gasoline flow rate by measuring how long it took to fill a 4 oz. shot glass. Thinking maybe there is a kink in the line. It took 20 seconds to fill 4 oz., so that is not the problem.
I appreciate all the folks that contribute to this forum and help many of us out. I look forward to hearing some other things I can go and check. Thank you for taking the time to read my post and respond.
Joking aside, 4 ounces in 20 seconds isn't the same as a pint in two minutes. Mathematically, yes, but not in reality.