COMET CENTRAL

Hi Guys:

Have a question...

The motor runs GREAT, but:

What is the ideal operating temp for a 390 GT 4V?

My car has the 7 blade clutch fan (new clutch) with the metal shroud since its an AC car.

Radiator and entire cooling system has been flushed.

Radiator is original but was re-cored at some point. Had it boiled to make sure it was clean and had no leaks...

It will sit and idle all day long at around 190-195. If I take it for a drive, come back and check the temp, the intake at the thermostat housing as well as the front of both heads goes up to around 200-205.

When I shut it down, the temp increases to 210-215.

The radiator has coolant at just above the top plate of the inside core...13lb cap I think....

All new hoses. Checked the bottom hose and it is not collapsing.

Motor seems too run fine even when warm, just want to make sure I am not running a brand new motor too hot.

Was thinking about going from the 180 thermo (think its a 180) too a 160, but I am concerned it might run hotter with the 160 if cooling is marginal.

I want to keep the car as stock as possible, or I would just put in a big honking aluminum radiator.

Thanks in advance for the feedback.

many yrs ago,I put a 289 in a 65 f100..still have it in fact,,,,it showed warmer then I liked on the gauge..and I knew for sure,my motor was not running hot......so I started changing out sending units in the intake til I finaly came across one that made the needle on the gauge read where I wanted it to..I'd change one out and drive it til I found the correct one....that may be your only problem.....or a bad in dash gauge........pop

I added one of those infra red temp probes to my tool bag when I started my project and it has served me well. About $30 at Lowes. Now I can point at any place on the engine to get a reading (regardless of what my gauge says). Just a suggestion.

Your temps are fine. It's normal for them to climb some after shut off. A 180 thermostat BEGINS to open at 180 if working properly.A 160 won't make it run cooler but just open earlier. It's a new motor. It might run cooler after it's bun run a while. Make sure the coolant level is always right and it's not blowing any out of the overflow. I know a lot of guys that would love to be running as cool as you are.

May just be the gauge. Do you have a new water pump on it? Might be the termostat is faulty. I have had bad ones right out of the box. (Over seas junk)

Matt

What vicegrip said.

WELL, OL POP is going to throw a bone in the meat grinder,,,,,I have a warmed over 390 4bbl holley,in my 66 f100 with a 3.50 rear gear,,has the original rad,that has never been reworked,but does have a tiny seep in the top tank when I tighten the cap,so I do not ever tighten the cap,it never ever runs hot,the needle on the gauge seldom ever touches the line,and I pull a race car sometimes with it or what ever I want to haul.the coolant stays half way,or just a tad lower in the top tank....the water pump is the same one that came off the 352 that I replaced with the 390....there's no telling how many yrs old it is..it goes not have a fan shroud,and it has the original fan,have to go look if it's a 4 or 5 blade,,heating problems just ain't in this ole 390's DNA,no matter the load or how you drive it,period ,,and the rad cap is never tight...

Hi Everyone:

Thanks for all of the comments.

To clarify: I am not relying on the gauge in the dash. It works, but I am actually using an infrared hand held temp gun so temp readings are actual.

I do not really care where the temp needle is on the dash, just need to know about where the needle ends up when its at a proper op temps...

I check it at the intake by the thermo, and I also shoot the front of each head.

To me, the temps seem to be a little on the high side, not much margin for error...

Its not boiling over. It did spit out some coolant at shutoff from the overflow, but that was early on and I think the radiator was simply over-filled.

Just trying to be cautious that I do not run a brand new motor too hot....

I re-did the timing and advanced it a bit from what I had it. I have read that if the timing is too far retarded that it can make a motor run warm.

Thanks for the input.

You worry too much. Read what boiling point water has at 13 lbs. The problem today is that we have too much information available. All modern stuff runs in the 230's. You have no problem at all. Stick your foot in it and smile.

SW

No worries, I have already had it floor boarded a few times and it hauls the mail for sure....

Really runs well, just making sure I do not cook it. My 351C 4V in my Torino runs at about 180-190, which is why I was concerned about the 390 running at over 200....

I checked today and my 390 has a 4bladed fan.......good luck !!....pop

Update:

I ordered a 160 thermo a few weeks ago when I thought it was running a bit hot, could not remember what I had put in it....

I had it in the right direction, and it was a 180. Moving it by hand it felt a bit sticky/gritty, so I decided to put the 160 in and see what happens.

With the 160 thermo, the motor idles around 170 ish, and after driving it around for 20-30 minutes, it climbs to 190-195. Much more acceptable than before.

Since it heats up driving it around ( 7 blade clutch fan) I am thinking that even though the radiator has been re-cored at one point and flushed, it might not be working at 100%.

So...today I ordered a 3 row all aluminum radiator. I am going to install the aluminum radiator and see if it helps it hold temp. If the new radiator makes it run too cool (under 180 or so), I can then go back to a new 180 thermo and see what happens.

Motor seemed happier and peppier at 190 than it did at 210+...

Will keep you posted.

Len

Hi Guys:
I solved the issue with the 390 running on the warm side.

It was running around 200-210, and temps would go up if I took it on long drives.

I was ready to install a new aluminum 3 row radiator, then I had an idea:

Instead of replacing the radiator, I decided to first try some of the "wetting" products I have heard about that you add to the coolant.

Took a drive to the Local NAPa store, and picked up 2 cans of Royal Purple "Ice" coolant treatment.

Went back to the garage, drained the coolant, replaced the 160 thermo (did not work) with a new Stant brand 180 with 1/8" hole drilled at the top, added the 2 cans of ICE, and walla.....the motor now runs 175-180 all day.

The ICE bottle said it would reduce temps by as much as 25 degrees, and it did exactly that for my 390.

Now I can move forward with refurbishing and installing the AC system.

So, for anyone that wants to reduce the operating temp, give the Royal Purple ICE a try, worked great for my issue....

we run that water wetter stuff in these race cars.....pop