Drove back from Carlisle yesterday (I live Northern MD) and ran into some single lane resurfacing - fresh blacktop so we had to slow to 20 - 30MPH.....and my temp gauge is bouncing around...oil pressure looked a little low...then once I got back up to speed all seemed OK. This is the third consecutive Carlisle event with the car and with this set up and never had an issue with this - the only difference was the new asphalt.
Car is a 70 Cuda Clone with 500 CID stroker, Edelbrock heads, 6 pack, 5 speed Tremec - 4:10 gears. Engine is 3 years old brand new, radiator is a 3 core and was cleaned and any necessary repairs were made - so it is good. Flex Flan (beginning to rethink that part), Thermostat is a 195 - engine has been rock solid at 205 ever since I put all this together. Running Prestone 50/50. Everything was fine when I got home - car restarted normally....
I was just wondering if the new black top radiated that much heat back into the engine (I have a Milodon 7 quart low profile pan)?

There is a lot of heat that comes off the black top, what made you chose that high a thermostat and I'd be loosing that flex fan. Do you have a shroud ?

I agree, you are already running at the upper portion of the scale so maybe the heat from the fresh hot asphalt might have inched it over.

Was thinking the same thing. I've never run mine without it and she's 190* all day long.

john whats wrong with a flex fan? the reason i ask is i've tried every kind of fan that will fit my 69 r/t (runs hot if you just look at it!) and i haven't found any difference in any of them.

Yes - I have a shroud though the leading edge of the fan is just inside the lip of the shroud. The reason why for the 195 thermostat - I am running a Six pack intake and was having issues with the idle - 1970 Plymouth Service manual as well as recommendations from MOPARTS members who had similar issues that I was encountering....which has really worked well...is there an advantage to a clutch fan Vs flex fan....I am also considering an electric fan just in case....though I really was hoping not to do that...thanks for the replies so far...

I have never had any luck with a flex fan.

You could try getting the fan into the shroud some and maybe that will pull more air ?

I can't see the logic of running the engine HOTTER especially if you have ethanol blended fuel , I would think that would make the idle worse once it got hot .

Do you sit with the car idling for long periods of time?

the 195 thermostat started in 1968 as part of the emissions packages. to say that a 6-pak has to have a 195 is silly.

I have to agree with this .

I have a 160 T Stat in my sixpack with no issues.

So, when did the six pack come out?

I'm thinking after the 195 thermostat.

With the gauge "bouncing around" I'm thinking the issue isn't coolant temp. The water temp gauge is slow acting, takes time to heat all that mass up. If it's bouncing the issue is in the gauge circuit. Is this a mechanical gauge or the factory one?

You could do what I do. I use a shroud I modified to fit and a flex fan which cools fine with my aluminum rad as it runs about 185 to 190 in average hot days. But if I get stuck in traffic and have to sit and idle to long on very hot days it will creep up to 205 so I figured I would add an electric fan for backup on a toggle switch I can turn on in traffic and see how it works. And it works great for me as even when I had to sit in traffic for 45 minutes on a 90+ degree day it kept it from going over 200 as it got up to about 200 and never went higher. It is a nice feeling having that backup for when I get stuck in traffic. A clutch fan is also nice and may pull more air at idle but I dont really have the room for the factory clutch fan and this setup seems to do the trick on my 63 with my 440 based 493. Ron

My setup is the same as 383man, no more heating issues. I had problems and learned alot from THIS THREAD .

I run a 160 thermostat, cheap black plastic flex fan(might upgrade someday), mechanical water pump, and I positioned the fan so it's part way into the shroud entrance. When I get stuck in traffic I flip on the 16" Be-Cool pusher fan, temp is always 180 or less, with a healthy 500" BB.

The closer to stock the better when it comes to old moper cooling systems. 7 bladed clutch fans keeps both my cars cool with no problem no matter what the temps or the surface. lol

I have a triple black 74 challenger with edlebrock headed 340 with a victor 340 single plane manifold and 600 eddie carb and AC.

I built it myself in 2007 with a stock bore 340 block and KB 243 10.4-1 pistons in it. That is the actual compression.
I have driven it 25K miles so far in some of the highest altitudes and the highest desert temperatures.

Twice we went to the top of pikes pike on the last day of July separate years. One time it was 32° at the top and cloudy. The second time it was 95° at the bottom and the park ranger came around to every car and told us to turn off our AC on the way up the mountain so we didn't over heat. I was nervous and turned ours off on our 74 challenger 340 equipped.

We were about halfway up and hit the gravel section, F it and we put the windows up and cranked on the AC. Made it to the top of that mountain with no over heating, not even close. The temp gauge went to 3/4 and stayed there. No air and 95° and it stayed cool.

I leaned the carb like 3 steps before I left Cincy because I knew I was going up pikes peak and cranked up the timing. No way it would make it with a Cincy tune I don't think because there was nothing left when I got to the top.

Then I have driven it with the AC on high for over an hour in Vegas stop and go traffic and Reno during Hot Aug nights and it's hot in stop and go traffic, twice in 115° temps. Cruised at night too, it was only 100°.

Lot's of black top everywhere, some of it fresh!!

Get rid of the flex fan first no matter what anyone says, that's my advise. To tired to search for pictures to prove I'm not lying

On the T stat, sounds like it was running over 205 F on the blacktop... at that point the 195 stat was full open so changing the stat would not help.

Blacktop radiates heat plus you were not travelling fast enough for good ram air (20-30 MPH not enough, 40-50 should be). At that speed you depend on the fan to help move air.

Sounds like fan + shroud might be the place to start. A thermal clutch fan + matching shroud is hard to beat... with a more aggressive fan since you are fighting cooling issues. Bouchillon has a nice clutch and 6 blade fan or the JY + AP store will work.

Again many thanks to the replies....the gauge is after market as it runs from the factory location - to be clear I have only encountered this issue this one time...the Milodon Low Profile Pan a bit more surface area closer to the asphalt....I have had zero issues with this set up with except this one time. clutch fan...maybe getting a longer spacer to move the flex fan closer to the radiator.....of all the things I have bought for the car a 7 blade clutch fan is not one of them....vendors or sources for them?

A 7 blade fan was used on mid/late 70's BB's... like my '78 Cordoba core engine. Probably others as well. The cleaned up original I have is on the shelf as diameter is too big for my muscle era spec shroud. The 6 blade Bouchillon fan at 19" works well for me with matching thermal clutch.

Does anybody know if the Flow cooler water pump from Summit is any good?It is supposed to reduce operating temps up to 30*,has double coolant flow at idle,prevents cavitation through higher system pressure.if you use this would you have to get a higher pressure cap?

Stock water pumps work the best for me on both of my cars. Drove both of my cars this week in the pretty high heat with no issues. My entire cooling system is mostly stock and nothing else is.

I just put a stock water pump on my 71 440 6 pak last week. It replaced the 10 year old one before it. I have driven the car over 100 miles in the last 7 days with it in pretty high heat, no issues like I said above.

I got the pump from Summit racing, they did not have it in stock. It took like 4-5 days to get to me. That says to me everyone is buying non stock pumps to try to solve other over heating issues.

Don't buy something after market and expect it to solve another problem with your setup.

Tune the car also to insure it's fuel mixture is correct. That means try the jet above what your running and below what your running now and then decide which way to go. It's fun feeling the difference and rewarding. That is one reason they can run hot, imo.

And no you wouldn't change the cap, it needs to be 15-16lbs. I am running 15# GM caps on both of my cars, 15 is not a problem verses 16#. For 4-5 years now I have been running those caps since the last of my OEMs ones wore out. Not saying it's best, it was convenient to pick out of Summit's catalog one day is why I have them.

I do not run a catch /recovery bottle in my 71, I do on my 340 lately(3years).
But did not have it when I went up pikes or Reno. Then had it in Vegas the second time I was there with the car, it made a positive difference. My temp gauge stayed more stable. I couldn't see the thermostat opening and closing on the temp gauge no more.

New water pump, I guess the aluminum water pump housing is not stock, sorry.

This is the old "Cat"(Chinese, didn't know 11-12 years ago when I bought it off E bay. Seal started leaking after a radiator flush a few weeks ago.) water pump I took out. I guess it is not stock because of the impeller? It worked fine just like the stock volume I just put back in with regular paddles on the impleller.

Here's the empty box with the brand name on it, stock volume pump that Summit did not have in stock.

Me driving the car last night in light rain sprinkles.


Oh yea, my 340 has a mildon 7 qt oil pan on it, it's wide at the bottom and closer to the ground than stock, it does not seem to contribute to over heating on my setup. I would think 7 qts is better than 5 heat wise? It was used in Vegas stop and go traffic at 110-115° temps on 2 different trips.