I'm extremely frustrated. I have seen similar postings to this, but I am pulling my hair out. I have a 1962 235 in a 49 Ton-and-a-half. It cranks slowly when cold but I can get it started. It runs and idles fine at about 650 RPM but doesn't want to idle slower. It will die. Then is will crank like the battery is bad. However, reading voltage at the starter it will show 6.25 volts or so. Here is what I have done so far:
1. Pulled plugs when warm... cranks at very good rate.
2. Starter completely rebuild with brand new high torque coils and new armature, bushngs, switch (foot starter), washers, everything except the case... by a very good shop.
3. Brand new commercial 6 volt battery.
4. Cleaned all terminals, connections, etc.
5. Read voltage drop from battery to starter... exact same readings.
6. Welding cable 00 for both hot and ground.
7. Moved ground to top mounting stud on starter at block instead of on frame.
8. Confirmed good 1" wide grounding strap from starter to frame.
9. Compression tested with readings ranging from 100 to 115 on all cylinders.
10. Used jumper cables in addition to usual cables from battery to starter... no improvement.
11. Tried using 12volt booster on starter directly along with 6V batter... no improvement.
12. Have had 2 6V batteries in parallel to get more current... no improvement. I used an Optima with a separate set of cables going directly to the starter.
This is not a case of "it won't start". This is a case of "it cranks too slowly like the battery is dead". If I can get it to spin up it will start. It will crank to speed with the plugs pulled, but even doing a compression test on one cylinder can cause it to stop spinning momentarily each time the piston comes up.
Please don't tell me to clean the terminals, rebuild the starter, and get a new battery. I have spent over $300.00 on all that stuff in the last week. This has been a problem with this engine ever since I put it in 5 years ago and that is why I gave up for a few years. I have decided to give it one last chance before I throw in the towel. Any useful input would be greatly appreciated.
