The heater has worked well since the second air purge. No issues today. The boy drove her about 35 miles without issue, just lots of smiles.
The key was getting all of the air out of the system. I got it to burp once on the initial coolant fill but there was still air in the system. Running the heater wide open with the radiator cap open and the nose of the car slightly up hill helped getting it to burp a second time.
For future reference the 65 temp sending unit and 68 temp sending units for a Mustang, while different in size, ohm out at the same value so they are interchangeable as best I can tell depending on what size your cylinder head requires.
My heater hose arrangement is basically as Bubba described above. The front short section of heater hose goes from a fitting on the cylinder head behind the t-stat housing to the front inlet of the carb spacer. Everything else is the same.
I got tunnel vision when looking for my vacuum leak to drop the idle down and focused on everything I intentionally touched and forgot to check at the vacuum modulator on the transmission. I only found it when we went for a test drive and there wasn't a 1-2 shift. As soon as that happened I knew that I must have bumped the fitting to the modulator valve when loosening the exhaust from under the car. Once the vacuum leak was identified and fixed, the carb was easy to set and the car performs better now than it ever has.
Again, thank you to all of the forum members that responded to my questions in such a timely manner. Without your knowledge, help and experience it would have most certainly taken longer to resolve the issue.
I hope this summary helps someone else down the road.
Kevin
The key was getting all of the air out of the system. I got it to burp once on the initial coolant fill but there was still air in the system. Running the heater wide open with the radiator cap open and the nose of the car slightly up hill helped getting it to burp a second time.
For future reference the 65 temp sending unit and 68 temp sending units for a Mustang, while different in size, ohm out at the same value so they are interchangeable as best I can tell depending on what size your cylinder head requires.
My heater hose arrangement is basically as Bubba described above. The front short section of heater hose goes from a fitting on the cylinder head behind the t-stat housing to the front inlet of the carb spacer. Everything else is the same.
I got tunnel vision when looking for my vacuum leak to drop the idle down and focused on everything I intentionally touched and forgot to check at the vacuum modulator on the transmission. I only found it when we went for a test drive and there wasn't a 1-2 shift. As soon as that happened I knew that I must have bumped the fitting to the modulator valve when loosening the exhaust from under the car. Once the vacuum leak was identified and fixed, the carb was easy to set and the car performs better now than it ever has.
Again, thank you to all of the forum members that responded to my questions in such a timely manner. Without your knowledge, help and experience it would have most certainly taken longer to resolve the issue.
I hope this summary helps someone else down the road.
Kevin