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Please tell me what your freeway temperature is. My 73 (72 chassis) 270 with a 413 runs hot on freeway but is fine at idle. A stock rebuild with an RV cam. Timing set at about 30 advanced total (hard to tell because marks only go to 15).\n\nAt about 65/70 mph and 3400- 3500 rpm runs between 210 and 235 (according to my autometer gauge) depending on how steep a hill. With no hill runs about 210. \n\nRunning a clutch fan with the stock radiator and shroud. Have a new water pump, rebuilt radiator, new 180 thermostat. \n\nI run a 16 inch aux fan on the front and a trans cooler. I am a bit concerned about all this stuff on the front of the radiator. The aux fan was on when I bought it so I am assuming it needed it so I am hesitant to take it off. I think I am also running to much antifreeze so I am going to dilute it some with water. \n\nThank you,\nKarl

I should also mention that I read the other posts that dealt with some issues with the 440 and replaced my cap with a 16lb. I also noticed someone mention that it was important to run a mopar specific thermostat. I got mine from Napa that was listing as fitting hundreds of cars. Just a generic 63mm. \n\nIs there a specific thermostat I need to run?\n\nWhen I get home I will have to check that I have the cap on right. I should also mention that I am not running an overflow because the fitting that come out of the filler piece broke off so now there is just a hole. \n\nBased on the other posts I am running hot considering the temperatures are mid 60's however I also have alot of steep mountains to climb.

A "Mopar thermostat" will look like the skirted unit on the left in the picture below.

That is interesting. Will have to try that.\n\nCould someone tell me what vehicle that fits for the parts store computer or a part number.

If the fan is in front of the radiator that could be your problem. They will actually block air. They are only good at idle.

highwaystar wrote:That is interesting. Will have to try that.\n\nCould someone tell me what vehicle that fits for the parts store computer or a part number.

\nJust ask for a 180 thermostat for a Dodge 440 anything... a 1975 Dodge 3/4 or 1 ton pickup or van for example.\n\nIf you google "4367 Dodge thermostat" you will see some pics.

Great info, thanks!\n\nDon't think I have ever seen that thermostat before but this is my first experience with Mopar Big Blocks. Have one ordered through Napa. It also dawned on me that I should also replace the clutch fan so ordered one of those. Would have been alot easier with the radiator out...\n\nBetween the aux fan and trans cooler there isn't much space on the radiator left. I am concerned that is part of the problem. I am assuming that the prior owner had cooling problems but I shouldn't assume anything. \n\nKarl

I am only running the factory fan... I would install a new fan clutch and ditch any obstructing aftermarket fans on the front of the radiator.\nJust FYI... my 440 idles at 180 and runs 190 - 200 going down a flat level road at 60mph. It will climb to 210 or even 220 on the hills but will slowly come back down to 200 again.

pulling 7 tons with a 440 is really a feat. Pulling a Dodge Monaco sedan was a feat... Any strong winds would push against the rv affecting gas mileage and raising temps..When going west to chicago etc and running into slight headwinds, temp would climb some what and mileage goes down. Heading east, with the same wind, mph and mileage would pick up and temp goes to thermostated controlled range. This was just from the winds...The temp rising under ANY loading conditions is to be expected..then you try drafting...The rv 440 is almost under a constant pulling load simlar to an outboard motor. Very little coasting... it's a wonder the motors last 100k ... not enough room to put all the tips you learn over the years in a 60 second column...again my opinion.\nBBB

Oh yea... I should mention that I am always pulling a 14' trailer loaded down with a golf cart and motorcycle.