model a radiator is it pressurized ?

fredski

fredski

Senior Member
needing a new rad or recore mine weeps in centre area, i have read that radiators for are cars are not pressurized , but some new replacements
are. what is the difference between the two. what should i have?

or am i confused again?

fredski
 
The original Model A radiator was not pressurized. The pressurized ones are usually used for street rods with later engines. The pressure allows the engine to run at a higher temperature (the boiling point of water goes up with pressure) and allows the use of overflow tanks. I would stick with the non pressurized for a stock car. Search the archives for comments about the best and worst suppliers.

Charlie Stephens
 
Charlie Stephens said:
The original Model A radiator was not pressurized. The pressurized ones are usually used for street rods with later engines. The pressure allows the engine to run at a higher temperature (the boiling point of water goes up with pressure) and allows the use of overflow tanks. I would stick with the non pressurized for a stock car. Search the archives for comments about the best and worst suppliers.

Charlie Stephens
Click to expand...

what makes a rad pressurized? a different cap that seals tighter?

so if using a non pressurized rad you could take the rad cap off when hot
with out it shooting out steam and water/


FREDSKI
 
not quite.

overheat the engine enough and it'll shoot steam like Old Faithful when the cap is removed .....

yes, even if the overflow tube is open! (re: next posting)

be cautious :-)
 
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In the Model A radiator the over flow tube vents the tank to the atmosphere. It the tube remains open you will not get pressure in the radiator and you don't have to worry about opening the radiator when hot. However if the tube gets clogged it will build pressure and spew. That has happened to me.

A pressure radiator has a cap that holds a specified pressure such as 15 lbs. the vent tube is above the pressure sealing part of the cap and if the specified pressure is surpassed steam and water flow out until pressure is equalized.
 
thanks for your explanations . i learned somthing again. tried to
find in search but without any luck.

fredski
 
In addition to the cap being different the radiator needs to be designed to take the pressure. Also the pressure will increase the probability that the water pump will leak. I must confess my dark side. I have a '32 Ford with a newer engine. There is no neck for the top of the radiator and I have attached a dummy cap from the underside. The neck for the pressure cap is under the hood (PM me if I am not clear).

Charlie Stephens
 
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Pressure systems in Model A's should use a very low pressure cap, like 3-4 pounds. I have future plans for a modified motor and opted for a new pressurized radiator even though my engine now is basically a B engine in a model a block. Brassworks built a nice radiator with an brass overflow that looks good and works extremely well. They also added a bung in the lower tank for a temp sending unit. I'm extremely pleased with the set up. I'm using a B water pump with no leakage problems.
 
Fredski, the reason for pressurizing is to increase cooling. It lets your radiator water run hotter without turning to steam at 212 drgrees F.

The reason your radiator will discharge more BTUs into the ambient air with hotter water....the heat exhange formula. Heat loss.= Area (of surface of rad) X U coefficient (The ability of the copper metal of the rad to conduct heat) X the difference of the temputure between the air passing over the rad and the water inside the rad. So, as you can see, if the water temp goes up the cooling increases.
You will eliminate some cooling problems with a pressurized rad, especially in stop and go slow traffic like parades.
 
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I am running the same thing as klawockvet .Pressurized BW radiator, 4lb cap and over flow bottle . Can see water level in radiator about two inches below cap . Advantages ; more water in radiator ,no water/antifreeze burping out over flow ,no guessing level of water in radiator , 12 degrees higher boiling point with water only . 224 degrees before steam . Once steam arrives cooling capability is lost .
 
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