Overheating above 1,000 rpm

Fresh 545 with dual 4 tunnel ram, aluminum heads, Comp Cams Big Mutha Thumper cam and valve train runs 185 when idle or around 1,000 rpm. Does fine idling down street, however the faster I go the faster the temperature climbs. Can not go more than 20 mph or it overheats.  Timing at 12 degrees initial.  Aluminum radiator with dual fans.  This is backwards to me, usually a car runs cooler at speed and overheats when going slow. Going 40mph it hit 215 in a minute, slowed down to 10mph and back to 185 within a couple of minutes. Any suggestions

545FORD wrote:Fresh 545 with dual 4 tunnel ram, aluminum heads, Comp Cams Big Mutha Thumper cam and valve train runs 185 when idle or around 1,000 rpm. Does fine idling down street, however the faster I go the faster the temperature climbs. Can not go more than 20 mph or it overheats.  Timing at 12 degrees initial.  Aluminum radiator with dual fans.  This is backwards to me, usually a car runs cooler at speed and overheats when going slow. Going 40mph it hit 215 in a minute, slowed down to 10mph and back to 185 within a couple of minutes. Any suggestions

Are you certain that one head gasket is not installed back-wards ...?
That is the usual symptom.

are your fans pushers or pullers?enough cfm?water pump ok? turning the correct direction?radiator plugged up? thermostat bad? etc etc etc.

Are you sure the heads was torque right just went through the same problem with my 69 had a head gasket leaking back into the radiator as soon as I would speed up my temperature would start climbing. I had a brain fart when I installed my AFR heads only torqued them to 70lb should have been 105lb plus my thermostat was sticking replaced head gaskets and thermostat and my problem was solved

rmcomprandy wrote:

545FORD wrote:Fresh 545 with dual 4 tunnel ram, aluminum heads, Comp Cams Big Mutha Thumper cam and valve train runs 185 when idle or around 1,000 rpm. Does fine idling down street, however the faster I go the faster the temperature climbs. Can not go more than 20 mph or it overheats.  Timing at 12 degrees initial.  Aluminum radiator with dual fans.  This is backwards to me, usually a car runs cooler at speed and overheats when going slow. Going 40mph it hit 215 in a minute, slowed down to 10mph and back to 185 within a couple of minutes. Any suggestions

Are you certain that one head gasket is not installed back-wards ...?
That is the usual symptom.

I am leaning towards your head gasket suggestion. Built the engine a couple years ago and I am usually very careful, but who knows. I found a good explanation about this on the internet.........
Most gaskets have the word "front" stamped on them. that edge of the gasket needs to be at the front of the engine for coolant to flow properly.
The water pump pumps the coolant into the front of the block. The FRONT of the head gaskets is blocked off so the coolant will travel all the way to the back of the block. It THEN enters the heads, and travels from the back of them to the front, where it exits the water neck and goes to the top of the radiator.
If the head gaskets were installed backwards (open side to the front) the coolant would simply go in the front of the block, flow straight up to the heads and exit the water neck. It would not cool the back of the engine. So yes, the water would flow, but no where it was needed. Next step is to see if I have a difference in temperature between the front and rear of heads.

Drivers side head temperature by each exhaust port is about the same.
Pass side head temperature about 30 degrees hotter on #4 port versus #1 port
Will keep testing other things to rule them out, but this is looking like the culprit.
I will also check to see if the head gasket is letting blow back into cooling system as 69F100 suggested.
I haven't ruled out timing too retarded as that can cause this sympton too.
Everything is new, radiator, hoses, aluminum water pump, expansion tank, dual electric fans (which have the highest cfm I could find on Summit Racing)Already tried another new thermostat, so I don't think I have any part failure issues.

The problem is, your engine is under the cab of the truck, and all the air is flowing away from it!!
Just kidding it's very likely the head gaskets.

Is there a spring in the lower rad hose. Without it they collapse when the water pump rpm comes up.

545FORD wrote:Fresh 545 with dual 4 tunnel ram, aluminum heads, Comp Cams Big Mutha Thumper cam and valve train runs 185 when idle or around 1,000 rpm. Does fine idling down street, however the faster I go the faster the temperature climbs. Can not go more than 20 mph or it overheats.  Timing at 12 degrees initial.  Aluminum radiator with dual fans.  This is backwards to me, usually a car runs cooler at speed and overheats when going slow. Going 40mph it hit 215 in a minute, slowed down to 10mph and back to 185 within a couple of minutes. Any suggestions

whats the total timing? these need min of 4500 cfm fans. best to rum them on inside as pullers, not pushers

Seriously, with your rad cap off, squeeze your lower rad hose. If you can collapse it by hand, that’s your problem.

While all the above may create or contribute to overheating, the one point that jumps out is how QUICKLY it heats up. The fans only matter from a stop to 30 mph with wind faster than that pushing more air than the fans can. The fact it doesn't COOL down above 30 leads me to believe you have a coolant flow issue.
Have verified coolant circulation with the cap off? I have never had dual fans cool as efficiently as a ducted single fan. I have been very satisfied with Spal 16" fans (pulling) and the Black Magic fan. You can pull 5000 cfm with a small fan but it won't cool well due to the small surface area it's pulling air through.

Which water pump do you have? I have heard high volume pumps don't allow the coolant to stay in the radiator long enough to dissipate the heat.