Cooling system info.

[RootesRacer]

Thx a bunch!

Now I wonder how this all works out becuase the stock cap is supposed to vent at 7psi. Based on this data, that cant be much more than 200 deg F.

Am I missing something?

 

[serIIalpine]

Jarrid

Have you tried the cap that VB sells for the early series car?

That may be where I got mine. They do seem to stock the odd stuff sometimes and while I'm loath to recommend them for almost anything they might come through.

Did you try a tractor store? You are in Colorado, They have tractors there.

I actually put a thick O ring under a stant cap I had until I found the cap I am using know in a box of parts. Worked fine but I didn't trust it.

And as far as my Weber linkage is concerned I know it isn't optimal but I need to find a center pull linkage that will work with the rod I have on there now.
I'll just move the mechanism to the rear carb when I do. I don't want cables running all around the engine compartment.

 

[RootesRacer]

Eric,

Yes I live in Colorado but this place isnt quite as rural as you may think.

I also tried an o-ring but if its not the same diameter as the filler neck, it will expand under pressure and leak from there. It did get me to beyond 1 PSI though, which is infinitely better than the cap itself.

You can use your weber linkage setup just be rotating it 180 degrees and having a bit of welding/brazing done to the link lever. Really is not that big of deal.
It will look every bit as good and be much more functional.

 

[serIIalpine]

Jarrid

I'm still not sure of the benefit of reversing the linkage as apposed to just putting it on the rear carb. Is there some reason why I shouldn't do this.

I really don't want my carb cables running up and around and then back to the linkage.

Thanks

 

[RootesRacer]

Jarrid

I'm still not sure of the benefit of reversing the linkage as apposed to just putting it on the rear carb. Is there some reason why I shouldn't do this.

I really don't want my carb cables running up and around and then back to the linkage.

Thanks

without coming up with a custom carb link, you need to put the opening pressure on the front carbs spindle lever.

Putting it on the rear carb works against the tension spring built into the adjustable (sync linkage).

 

[bobw]

Thx a bunch!

Now I wonder how this all works out becuase the stock cap is supposed to vent at 7psi. Based on this data, that cant be much more than 200 deg F.

Am I missing something?

In a closed container the pressure you see is determined by the temperature vs vapor pressure for the mixture you have. As Bill Blue mentioned, if you have the system totally full of fluid, you will get an immediate rise in pressure, due to the expansion of water, that doesn't follow the curves in the chart because water doesn't compress. An "expansion" tank should always have enough room for the water to expand.

The newer systems that are filled to the top use a "recovery" tank to store the water pushed past the cap, and return it to the system when temperature is reduced. No direct relationship to pressure and temperature. The pressure can actually be below 0 as the mixture cools.

From the chart, a 7 PSI vapor pressure occurs at about 190F with a 50/50 anti-freeze mixture. Above that temperature, some vapor/coolant will be expelled past the radiator cap. This vapor escape will also provide some cooling as the hottest molecules are the ones that escape.

Of course, the cap has to seal and be working properly. Otherwise it's just like a pot of water on the stove. The higher the temperature, the faster the mixture evaporates. Over time, I think you would get a higher concentration of ethylene glycol as the water would evaporate faster.

BTW, take all the reading I make from that chart with a grain of salt. My eyes seem to cross every time I look at it.

Bob W.