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Username Post: Over heating        (Topic#348960)
Posts: 273
Loc: Davenport, IA
Reg: 02-18-04
01-01-18 12:18 PM - Post#2719683    

I have a 261 in my 53 Chevy that I installed a/c into. When I drive it up around 75 MPH with the a/c on it want to over heat, above 220. It run a little warm at lower speeds also. It has electric puller fan and shroud in back of the radiator and two pusher fans in front of the condenser. The timing is good and I have changed the temp of the thermostat a couple times. I have a 3 core aluminum radiator on order. I'm now looking at going to a larger water pump pulley. Maybe 7 3/8" or larger size pulley. The theory being to slow down the water flow through the radiator to cool it down better. Looking for suggestions on where I might find a larger pulley to fit the bolt pattern of my water pump. Needs to be a two groove pulley for the short water pump.


"6th Year" Silver Supporting Member
Posts: 953
Age: 61
Loc: Wisconsin
Reg: 07-25-11
01-01-18 02:08 PM - Post#2719694    
    In response to 53Chevy

You say the timing is good. Was it timed by the marks?

Well, you know what's wrong with the world today

People done gone put their Bible's away

They're living by the law of the jungle not the law of the land

"Simple Man" By Charlie Daniels

Silver Supporting Member
Posts: 1051
Age: 62
Loc: Basehor Ks
Reg: 02-11-13
01-01-18 02:40 PM - Post#2719698    
    In response to 53Chevy

The timing is where i would look first, If you get into total advance around 32 -34 degree's you could overheat at higher RPM's.

Second what pressure radiator cap are you running and where is the coolant level at.

Third any cracks in the head or block or a bad head gasket ??

My built 261 runs 160 temps max on the road in 90 plus heat with the A/C on i am running 32 deg total advance timing 3 core alum radiator and dual 11" pusher fans.

Bel Air kiwi 
"3rd Year" Silver Supporting Member
Posts: 4260
Bel Air kiwi
Loc: New Zealand
Reg: 04-24-14
01-01-18 05:05 PM - Post#2719714    
    In response to cbmkr56

Hi Guys, I think the idea of slowing down the water pump to improve cooling is a bit of an old wives tale.
The only reason I have seen them slowed down is in endurance racing of near production cars where they are running to red line as often as they can.

In these cases it can save Hp or take a pump below its level of cavitation, where its spins in the water in a turbulent mess rather than pushing water through.

I am familiar with the Ford Cleveland which has a brass plate restrictor under the thermostat. But my understanding is this is a fix for coolant not going to the desired places, and running without it can cause failures.

However in general terms the heat differences in metal to water are very broad and so heat transfer is immediate.
This breaks down when you get localized hot spots that create steam pockets as steam is a relatively poor heat conductor compared to hot water.

If you put a 235 head gasket on a 261 you can get this problem as the 261 has more transfer or "steam holes", because it needs them.

The best way to get your head around what your cooling system needs is to understand two important ideas.

First is that an engine with a radiator is still air cooled, it just uses water to transfer the heat from one place to another.

Second, for every quantity of fuel you burn you get one unit of power and between 3.5 to 4 units of heat.

So almost all overheating problems have at their core (Pun intended) that not enough cool air is flowing through a large enough area of radiator.
You can make it worse by running too advanced or too lean but these are minor issues.

Water wetters, high system pressures, etc are all fudges that mask a fundamental lack of system capacity.
OE makers want to fit the smallest radiator that meets their obligation for all the market conditions they warranty for. Because radiators use expensive materials.

If you come along and change the parameters then don't expect to have the margin built into the OE system.

Firstly get the biggest capacity radiator you can stuff in place, followed by the most effective fan system, then eliminate all obstructions that folk are so fond of blocking radiators with.
There is absolutely no reason other than cost saving for having your trans cooler or oil cooler in or in front of the radiator. They act as a flow restriction and pre-heater to the radiator.
Air-con condensers are harder to move so you have to compensate for their effect by adding air flow and radiator capacity.

Fan shrouds improve fan efficiency a helpful amount and are important. But if you are stuck in traffic with the air con on the engine driven fan is just ticking over and to get a faster fan in that circumstance you will need to go to electric types.

Cheers Kiwi

PS. if you believe a slower water flow improves cooling then it follows that leaving your hand in the flame longer will reduce the burn. We all know that ain't so.

48 3100 RHD, 51 Deluxe 4DR RHD, 51 Bel Air parts car, 52 Bel Air P-Glide LHD. Others 23T, 32 Tudor, 58 Edsel pacer 4DR HDT, 79 F250 351C RHD. 69,70,82 Capri. No mobile, no TV, and no Jap cars.

And when it was laid to waste, they called it peace.

Edited by Bel Air kiwi on 01-01-18 05:30 PM. Reason for edit: No reason given.


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