All Small Six Chasing vacuum leaks.. solved ..but now overheating.

[sixtseventwo4d]

You also need to see what your maximum timing is at. I use a digital timing light with adv/ret feature to know where it's at and at what rpm

 

[John Ha]

So I took it out for a drive and it gets hot very quickly. I have a given it new 180 thermostat, new water pump, new aluminum radiator, timing is 6btdc (was 10 then 8 now 6) and it’s still overheating the same. AFR gauge is 10.7 at idle 800rpm and shows 11.5 while driving steady at 55mph. Cold It starts up and runs no choke (manual choke off). Hot also starts easily just turning the key with no pumping the gas or excessive cranking and will idle no issues except the getting hot and blowing out coolant.
I drove it 10 miles and it ran ok, a bit sluggish on acceleration but cruising along at 55 with ease. Sat at just under boiling the whole way.Spewed out coolant from the overflow when I turned it off. Let it sit for a few hours and topped off the radiator with almost a gallon of water and drove home and it ran the same as it did on the way out and dropped a puddle of coolant when I got home. If I can figure out this overheating bit it might be a good daily driver.

How are you determining when to stop adding coolant when it's cold? Normally the Mustangs like to have the internal radiator fins covered by about 1/4 inch of coolant. Much more than that will end up spewing out the overflow. Have you run it for a while after you see the coolant circulating with the radiator cap off and added coolant as needed? This will eliminate air pockets in the system.

As far as the "sat at just below boiling", remember that it's a pressurized system and that being under pressure raises the boiling point of the coolant. As long as your gauge is steady, it sounds like the system is working like it's supposed to.

As far as the sluggishness, what is the distributor vacuum advance connected to - full manifold vacuum or ported vacuum?

 

[ActionYobbo]

I have the original carburetor rebuilt and back on the motor and the original distributor and coil. I have the radiator out getting ready to put the original radiator back in when I finish cleaning it. I started flushing the coolant system last night. I should have it ready for another drive soon.
To answer some questions
I assume it’s full of coolant when it can’t take anymore. I had it running and kept adding coolant when there was room.
The vacuum advance was not hooked up when I was using the electronic distributor now it has the original distributor hooked up like ford did it. I have it running but have not taken it for a drive since changing back to the original parts.

 

[63 Sprint]

Small Block inline sixes are known for timing chain stretch. There is a simple way to check if the chain is still within spec. I don’t have the procedure saved to check. Maybe another member can assist. This should be checked on any Small Block inline sixes.

 

[sixtseventwo4d]

It can be difficult figuring out if you're solving it or causing it whenever changing more than one thing at a time.

 

[ActionYobbo]

Another update. I found the bottom hose was sucking flat behind the power steering bracket. So I have replaced the hose and filled the radiator with what it could take then ran it for a bit and now I am waiting for it to cool off a bit before filling the radiator with more coolant then I hope to go for a long spin with out any more problems.

 

[rickwrench]

Might be a good idea to back flush your new radiator with as much flow as you can manage, then install a Gano type inline radiator filter in the top hose. The blocks are 50-60 years old now, and full of flaking crap that comes loose, flows to the radiator (or heater core), and plugs up core tubes.
Running a spring reinforced lower hose is also a good idea. Overflow jug is needed, blown coolant gets sucked back as when the system cools off.
Already mentioned: Advance 'till ping, back off a bit from there.

I've pulled a surprising amount of crap out of the radiator filter over the years.

 

[Frank]

Overflow tanks are 10 bucks on Amazon, easy install and totally worth it. The radiator can be kept full and no expensive coolant is lost when it heats up.