I would say your temps are fine but I would be a little concerned why the engine temps are so much above your t-stat opening temp..Especially if it hasn't been that hot outside...My 408 runs right on the 180 T-stat opening point..

 

That's my question too. The level in the overflow canister raises about an inch over the cold mark and that's where it sits. I did do a test with an analog gauge in the radiator when I had the 195 t-stat in and the coolant temp never got above 180. I'll have to try that again now that I have the 180 in there. Seems like the temp at the sensor (located on the driver side front of intake manifold) doesn't match up with the temp at the t-stat (passenger side front of intake). If there were real over heating issues, wouldn't it keep rising till it boiled over? I've driven if for a good 30 minutes straight in around town driving and it never goes past 200. I've thought about trying a 160 t-stat just to see if it then sits at 180 since it sat around 210 with the 195 and 200 with the 180.

 

I'm guessing that the problem is difficult to fix because it is probably an airflow problem with the 65/6 bodystyle. I have a 351 in my '67/8 with a 4 core aluminum rad and dual electric fans that runs at 180 all day long. Unfortunately for you, your engine bay doesn't have that much clearance and your front end is pretty restrictive on airflow.

 

Yeah, it's tight in there. How about dropping a 160 t-stat in? I know the t-stats don't fix over heating issues, but from my tests so far the radiator / fan seem to be keeping the coolant mixture below the installed t-stat temp.

 

If you have a 180* thermostat and the engine runs between 195-200* then with a 160* thermostat the engine will run between 195-200*. With a 195* thermostat it should also run at 195-200* assuming that the temperature gauge is accurate (most are lucky to be +/- 10%, unless you're running an old school mechanical gauge with a thermocouple, which are a BIT more accurate but still could be +/- 10*, especially if made in China).

Try and get a reading from a non-contact pyrometer from the thermostat housing. A daub of flat black paint will yield a better reading than bare cast aluminum.

As far as 195-200* goes, that's just about perfect.

 

This! ^^^^^

 

180* for carb and 195* for fuel injected.

 

You're right bartl. Put in a 160 and it inched its way to 200. If it starts to go higher i'll throw the 180 back in and stop fretting over the gauge.

 

FWIW, 195* was the rating for the OE thermostat.

 

You might have to do some reading on electric fan set ups. When I had one in my '68 I set it to mimic the fans in the injected cars which were driving 15,000 miles a year. The fan came on with the a/c or around 190 or so. Heck, this Aurora pushes the high fan turn on to 218ish! But I was trying to be conservative.

But yeah, if your Mustang idles on a 95 degree day in traffic at 195 I would be thrilled.

Next thing I am looking for is to fix air sneaking around my radiator.

 

I started with a 195 but it would constantly move between 200 and 210 with that setup.

 

I'll try the black paint for the temp gun too. When I had the 195 in there and was doing all those tests, I was also checking all around with one of those infared temp guns. The only thing that reached 200 was the block. All other locations based on the gun were well beneath that.

 

Saga continues. Last night after installing the 160 I drove about 6 miles, two stop lights and average speed of 45 mph. Car got up to 200 temp outside was probablly high seventies. Let it cool down and added more distilled water. Drove to work today, about 8 miles, avg speed of 40, about 4 or 5 stop lights / signs...gauge sat at 180...outside temp probablly high sixties. Its probablly going to get into the high eighties today so I'll see what happens when I drive home at lunch.

Just leads to more questions though. Gauge seems to run 15 to 20 degrees higher than the installed t-stat. Like I mentioned, I've used a temp gun all around the engine several times and temps were always lower than what the gauge indicates. My gauges are all new electronic from New Vintage. Early on I contacted them about the calibration of the temp gauge and they doubted it was off but said I could add a resistor into the sending wire to drop it down. Before doing that I want to make sure I know what temp reading is correct. Can the temp sender be tested by putting it in a hot cup of water or does pressure play a part too?

 

…and finally remains between 195 and 200.

Sounds like you are nailing factory spec.

 

Yeah, with the 180 t-stat that's where it lived, but it changes with each t-stat. This morning with the 160 it sat at 180. What I really want to do is test the gauge to see if it's off 15 to 20 degrees.

 

Talked to new vintage again today and they told me to take the teflon tape off the sender. That seems to have done the trick. Now for the big debate...180 or 195 tstat?

 

180.

 

Buy a cheap gauge from Autozone and see what it reads. If it's lower, your new Vintage gauge is your problem.

 

Reading the posts I did not see anyone speak to ignition timing or your air fuel ratio. Try running more advance as its a free test. Also insure correct AFR over the rpm range.

 

Just wanted to add the final fix for this post. Turns out removing the teflon tape didn't fix the problem. I used bartl's suggestion and put a couple spots of flat black paint on the manifold near the temp sensor and water neck and the temps from the thermo gun were consistently 15 to 20 degrees lower than the gauge reading. So I ended up putting a 33 ohm resistor in the sender's sending wire and the gauge now matches the temps from the gun. Car is running steady at 180 on the gauge and thermo temp gun confirms it.