The Stovebolt Site Forums The Shop Area Engine Shop Hard starting when engine is warmed up

I have recently fired up a 1961 model 235 mated to a 1946 transmission with foot pedal start. The engine fires up and runs great albeit a bit loud with headers and short pipes ending under the seat. The problem seems to be that after driving for a bit, still in the “working the bugs out” phase, it was hard to start again.started up and went for another test drive. This time the engine would barely turn over . It sounds like the starter is fighting the engine to turn over, almost like it’s out of time. Tried again the next day and it fires right up and runs good. The dash gauge doesn’t show a discharge with just the engine running. I’m using a 12 volt system with generator. Any ideas? I’ll check the battery just to make sure it’s not being pulled down if the generator isn’t putting out the proper charge.

Check your battery cables and make sure they are in good condition, along with checking for clean ground and clean connection to the starter. I have had similar symptoms with two different trucks. One was a dirty ground connection with the frame and the other was a loose connection of the positive cable with the starter. The poor connections act like a resistor producing heat, which leads to more resistance and then you can't get enough current to operate the starter.
Kent

Also, depending on how close the headers run to your starter, they will prevent the solenoid from working. Ask me how I know

Even if its not the current problem, like pan3lman said, headers and starters dont keep good company. Ha, i guess they like social distance. I would find or make a heatshield for the starter in the near futire. If it aint a problem yet, it will be.

I'd really like to see a 235 exhaust system that's capable of getting the exhaust anywhere near the starter. You need to do a voltage drop test across every connection from the battery to the starter and back while the "slow crank" situation is happening. Back in the dark ages when mechanics actually performed diagnosis procedures instead of just shotgunning parts at a problem, we called that a "series resistance test".
Jerry

I had the same problem Kent described ,would start right up after engine warmed up and shut off truck would have a difficult time starting up .I found it would start right up if I parked on a hill and rolled down and let the clutch out in gear.It turned out it was a bad ground that got worse when the engine heated up

Thanks Hotrod Lincoln. Yes, the headers and starter are on opposite sides. I have been running the engine while only putting the negative lead on the battery by hand. Perhaps that is the problem, or at least part. I’ll check the rest of the circuit, too. Thanks Kent for the insightful reply.