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blkcorvair
Jedi Knight
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I saw as a part of a post on here, radiator cap pressure and it's cooling effects, I Figured Id start up a post dedicated to Radiator caps, as I never really though about what would be best to run. Any Ideas?
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Radiator Caps
- Thread starter blkcorvair
- Start date
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One that seals properly in the rad or pot neck?
The correct pressure for the rad. configuration and water pump shaft seal ?
Unless the cap is mechanically defective there is usually no problem with caps. Problems loom with improper or inadaquate air and water flow thru the rad core. (engine condition permitting).
The correct pressure for the rad. configuration and water pump shaft seal ?
Unless the cap is mechanically defective there is usually no problem with caps. Problems loom with improper or inadaquate air and water flow thru the rad core. (engine condition permitting).
OP
blkcorvair
Jedi Knight
Offline
I read here once that putting a higher psi cap can result in adverse effects?!?!? What is it supposed to be normally?
aeronca65t
Great Pumpkin
Offline
I'm running a 13 lb cap in mine (on the standard little reservoir tank). I think that's stock.
No problems to date.
Mine never gets near 200F and I never lose any coolant.
I have no fan of any type on mine.
I'm running 100% water (required for vintage racing) which should boil out a bit quicker.
No problems to date.
Mine never gets near 200F and I never lose any coolant.
I have no fan of any type on mine.
I'm running 100% water (required for vintage racing) which should boil out a bit quicker.
Radiator caps...
I have a couple of bugeyes with vertical flow radiators with 7 lb caps.
I found the best cost affective upgrade was to add a $8 small over flow reservior kit from my local auto parts store.
The kit comes with a rubber gasket that you put on your reservior cap and you never again take it off. You now fill the radiator thru the reservior tank connected to the over flow tube on the radiator. The radiator is now always full. I can run at 220 to 230 and I <span style="text-decoration: underline">never</span> boil. The pressure increase in the system seems to let you run a hotter with out problems.
On my MGA I run a radiator cap with the rubber gasket already installed (MGA guru site), but I haven't found the part number for the bugeye radiator cap that has a rubber gasket on it. If anyone knows that is the radiator cap to get!
Liam
I have a couple of bugeyes with vertical flow radiators with 7 lb caps.
I found the best cost affective upgrade was to add a $8 small over flow reservior kit from my local auto parts store.
The kit comes with a rubber gasket that you put on your reservior cap and you never again take it off. You now fill the radiator thru the reservior tank connected to the over flow tube on the radiator. The radiator is now always full. I can run at 220 to 230 and I <span style="text-decoration: underline">never</span> boil. The pressure increase in the system seems to let you run a hotter with out problems.
On my MGA I run a radiator cap with the rubber gasket already installed (MGA guru site), but I haven't found the part number for the bugeye radiator cap that has a rubber gasket on it. If anyone knows that is the radiator cap to get!
Liam
Jedi Warrior
Registered: 05/25/07
Posts: 732
Loc: New York I read here once that putting a higher psi cap can result in adverse effects?!?!? What is it supposed to be normally?
Lot of the old radiators wont take big time pressure. Most of the downflow (older car) rads pre 66 or so....had caps 10psi or under. Crossflow radiators have stronger construction (usually) and used 13 or even higher caps. What o.e.m. over the years has done is decrease radiator capacity and increase cap pressure, but the rad cores and cooling systems have been designed for big pressures. An earlier rad that has been refurbished and looked at by a rad shop and pressure checked to 35psi certainly can take a 16# cap without adverse effects. Cross flows work better with higher pressure caps also. Every pound of cap pressure raises the boiling point about 2.2 degrees F. So straight water with a 10# cap will thoretically boil at 234*F. Add 50% glycol and you pick up another 20*F. maybe more (look on the bottle label).
Lot of the early water pumps with rope seals and not ceramics are problematical running at high pressures. On the race car I use just enough to get by......13# cap and a coolant over flow bottle. If you have decent airflow thru the rad and a rad of sufficient capacity and area and a decent fan for street use, you should be able to keep the operating temp where you want it. Example here is Spridgets both A motors and 1500's are happiest at about 175*. Having a good cooling system, using glycol and a minimal cap ...say 7 # you will have loads of cushion on the hottest of days.
On a street car its best to use a cap that has the O.E. pressure or maybe only 2 or 3 # more. This keeps stress off hoses , rad tanks and pumps.
"""""Nial sez
I'm running 100% water (required for vintage racing) which should boil out a bit quicker."""""
yes it will as I said above,212 + 2.2x13 = about 240*F before boiling. I believe in Redline Water Wetter; 1/3 bottle. And a dash (about 6 spoonfuls) of Prestone rad lubricant. Water wetter is a surfactant and will lower the rumnning temp. It works....I rally dont need it but I still use it.
"""""Liam writes"""""
The kit comes with a rubber gasket that you put on your reservior cap""""
If you get the good overflow botle in the green box, it comes with a 13# cap which might be 2 much pressure for you. What you want to use then is a cap that fits YOUR neck and that has TWO GASKETS in the cap...one at the botton and one just under the top..this allows water to go both ways.
Keep cool...........
Registered: 05/25/07
Posts: 732
Loc: New York I read here once that putting a higher psi cap can result in adverse effects?!?!? What is it supposed to be normally?
Lot of the old radiators wont take big time pressure. Most of the downflow (older car) rads pre 66 or so....had caps 10psi or under. Crossflow radiators have stronger construction (usually) and used 13 or even higher caps. What o.e.m. over the years has done is decrease radiator capacity and increase cap pressure, but the rad cores and cooling systems have been designed for big pressures. An earlier rad that has been refurbished and looked at by a rad shop and pressure checked to 35psi certainly can take a 16# cap without adverse effects. Cross flows work better with higher pressure caps also. Every pound of cap pressure raises the boiling point about 2.2 degrees F. So straight water with a 10# cap will thoretically boil at 234*F. Add 50% glycol and you pick up another 20*F. maybe more (look on the bottle label).
Lot of the early water pumps with rope seals and not ceramics are problematical running at high pressures. On the race car I use just enough to get by......13# cap and a coolant over flow bottle. If you have decent airflow thru the rad and a rad of sufficient capacity and area and a decent fan for street use, you should be able to keep the operating temp where you want it. Example here is Spridgets both A motors and 1500's are happiest at about 175*. Having a good cooling system, using glycol and a minimal cap ...say 7 # you will have loads of cushion on the hottest of days.
On a street car its best to use a cap that has the O.E. pressure or maybe only 2 or 3 # more. This keeps stress off hoses , rad tanks and pumps.
"""""Nial sez
I'm running 100% water (required for vintage racing) which should boil out a bit quicker."""""
yes it will as I said above,212 + 2.2x13 = about 240*F before boiling. I believe in Redline Water Wetter; 1/3 bottle. And a dash (about 6 spoonfuls) of Prestone rad lubricant. Water wetter is a surfactant and will lower the rumnning temp. It works....I rally dont need it but I still use it.
"""""Liam writes"""""
The kit comes with a rubber gasket that you put on your reservior cap""""
If you get the good overflow botle in the green box, it comes with a 13# cap which might be 2 much pressure for you. What you want to use then is a cap that fits YOUR neck and that has TWO GASKETS in the cap...one at the botton and one just under the top..this allows water to go both ways.
Keep cool...........