You had said idle was ok, so I thought the difference in driving is more heat and more air flow thru the radiator. Your air only changes in front of the fans. The remaining air does't flow thru as it should. How much, I'm not a engineer, so I can't say.

Since your hood tilts forward, a piece of foam, etc and something to restrict movement such as light ropes on the sides wouldn't hurt the paint and no danger of the hood flying open as it might with a front opening hood. Definately want to be safe when testing anything.

Thinking of the old metal fan and shrouds and how they funnel the air towards the fan center from the edges.
Is two gallons the normal amount of coolant for your engine block and radiator. I don't know.
chuck

 

2 gallons is about 1/2 gallon more than stock.

Sam

 

49pickupemup's #3 is likely your answer, and as Tuck says, Randy fixed it by removing the shroud. Your net flow area thru the radiator is the area of those two fans, probably less than 60% of the total area. The fans have all the shroud they need integral to themselves.

I assume you mean your radiator is copper, not steel? And 6 row? That is unusually deep and may actually be hard for air to flow thru.

Tranny heat is about 20% of engine HP under the worst conditions, so I doubt that is the cause. Most of the time it is more like 10%.

 

sam you've had so much trouble with things but i am gonna ask a real obvious and dont throw rocks at me question ....... you dont have a head gasket or intake gasket leaking oh so slightly into the cooling system do ya ??????????? be real suprised how that gets overlooked as it's a new engine , AND everything should be right .......................

 

good questions... I don't see any loss of fluid, and no bubbles in the rad neck typical of a gasket leak. are there other ways to check this? We didn't detect any of this on the dyno. (and given enough water flow on the dyno the temp held at 165).

Sam

 

sorry, yes copper. yes, I have worried about the depth lately too.

Sam

 

Just a couple of thought's...

Did you open the heater valve to wide open 'full-heat' when first starting,this will allow any air trapped in the heatercore and hose's to move thru the system and not createa large air-pocket..sometimes the unusual routing of hoses in 'custom' applications can cause some weird hang-ups.

I use a small hand-held digital infra-red themometer all the time to check cooling woes and flows..when the t-stat opens and closes, where/hot-spots may be in radiators and for verifing temp swx operation. They are not too expensive..around $ 75-$ 100 bucks, but worth the investment.You can easily watch " liquid " temps, but for air temps you will need a different method. Good Luck!

 

thanks..

however, I was incomplete in my description

the first 3 overheats were all in stop/go traffic during the Woodward cruise on 8/14-15. so, in this case the shroud removal would not be a factor as I was barely doing 5 mph (when moving).. so I was completely dependant on the fans. This is also the worst case for the torque converter generating heat.

this should have been not much worse than idle for engine generated heat, which is what I was doing most of the time.

Sam

 

yes, opened the heat valve, and also did so during the overheat periods in stop/go..
this helped delay the issue..

the infrared thermo.. NICE idea.. I was wondering how I might tell if the rad was doing its work by checking temps.. do you have any experience on the temp difference top (inlet) to bottom(outlet) on the rad?

Sam

 

If this were a flathead, the first thought would be incorrect timing, so that's worth checking too.

 

thanks.. right on the mark off the dyno..

Sam

 

TCI Auto (torque converter) recommends an external cooler, temps going TO cooler could be near 300 degrees in stop & go traffic.

they also said to measure temp at the tranny pan for the most consistent temp.

My wife just picked up the laser thermometer at HF (nice she was going by from the doctors visit).

Sam

 

my flatty had several small leaks around water ports in the head gaskets , that werent even showing in the radiator for a long time , ran warm , but never overheated , till just before i parked it then it popped the seem again on the old radiator , but still got me home and never over heated ! just had to add water every couple of days { antifreeze }. ran a compression leakdown test and found 4 out of cylinders were 93-95 pds of pressure the other 4 were way above what i expected , 125 pounds ! so may not be completely noticeable at first , and though i may not seem like it at times i am a competent mechanic so ......... also check the air bubble thing as well as the capacity . my 429 bird of 70 vintage had a huge by huge radiator , bigger than my 83 4x4's in length and dain near in height , and was 4 core . my current bird and the flatty even gave me fits getting all the air out of 'em at first !!! big horsepower / engines = big cooling systems in my old mind .

 

I had a 78 F-150 with 460 and like you say, the radiator was about 3+ ft by 30" or so, simply massive (and $$$$). It could be you just don't have enough radiator.

 

Sdetweil-

I have just completed Overheating 101 with my truck (1955 F100 390/C6). After reading all the posts, I have one suggestion that wasn’t previously mentioned. Here goes… Is your carburetor running lean? Your idle circuit could have a good A/F mixture thus, you are not overheating when idling in the driveway. However, if you are lean with your primaries this could cause you to run hot as you transition out of the idle circuit into your primaries. This is an easy adjustment to make and could rule out another variable. Just a thought.

Lance