Car is a 1966 mustang 289 automatic with air conditioning

With and a/c on and an air temperature of 100 degrees engine runs at a steady 210 degrees
With car idling in drive the temperature continues to escalate gradually.I shut it down at 240 degrees. I shut of the a/c and run the engine at about 2000 rpm while sitting and it cooled down to 220 degrees.

The car has been restored with the following being done

Engine was rebuilt and it has 100 or so miles so should not be real tight
All hoses, heater core, water pump, thermostat, fan clutch, spring in lower hose and radiator cap were replaced
Radiator was replaced with a low buck 3 core brass and copper one
Stock fan shroud was added

Car has a 7 blade stock mechanical fan. Engine timing seems to be correct. Head gasket appears to be installed correctly.
Pressure test of system was good

I am out of ideas as to what the issue might be.

Thanks for any comments

 

What temp thermostat? Could possibly have air in the cooling system. I would start with verifying no air first as that is the easiest and cheeper fix

 

If memory serves me correctly 192 degree.

 

how do you know it was at 240f?
With it in its current configuration did it ever work right in 100f weather?
How long has been resorted in this current configuration?

I have a well built 302 that produces about 290 RWHP. Even with quality aftermarket radiators it would push 212 in traffic in 100+ weather. I dont have AC but suspect that it would have been asking quite a bit from that system even with its high efficiency high dollar radiator. Probably doable but right at the edge of failure.
I installed a radiator built for a 68 mustang, cut some rad supports and made some simple brackets. It has about an additional gallon of cooling capacity and in traffic I have yet to push it above 189f with a 180f tstat that took about 110f out side temp.

-Gun

 

Temperature was measured with a mechanical temperature gauge installed in the stock sender location

In the current configuration it has always run hot which is why I am looking for ideas

It has been setup this way for several years but only recently did I decide to give it the full stress test

 

does the fan shroud fit properly?
how much was engine bored out?
how much HP does engine produces is it well built or pretty stock?
Can you post some pics?

 

does the fan shroud fit properly? I believe so. Factory shroud with blade about 1/2" into shroud
how much was engine bored out? 30 over
Stock rebuild
I did back off the timing about 2 degrees and it seems to heat up a slower and did not overheat after idling in park with a/c on with air temp of 102 degrees in 15 minutes. Might have overheated if it had run longer. That may be as good as it gets
I do have vague memories of running in the 1960's just water and anti rust in the summer which will dissipate heat better than antifreeze water mix.Maybe that is what Ford did.

 

If its a stock rebuild with 30 over you would expect a stock system to run pretty well.
How much timing are you running?

Between having .30 thou less cylinder wall what could be a radiator less than factory quality could do it.

That radiator might be a total pos? that seems most likley at this point. You could try a quality high efficiency al radiator thats a direct fit... is my only suggestion at this point considering its never run right.

 

Backed the timing down from 8 before to 6 before. The radiator I bought about 3 years ago was only $139.It looks fine but I do wonder about the quality at that price.

 

is that base timing or total timing?

How much total timing are you running say at 3,000 RPM and how much timing do you have at idle?

EDIT: How much cooling differential do you have. That test could prove that the radiator is bad. How hot is the top of the radiator (non contact IR temp gun) VS the bottom of the radiator. Check after driving with engine running if possible