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Discussion Starter #1
I have a 615ci BBC with 10.8 compression, big bumpstick, two 1050s on a Dart tunnel ram, aluminum heads...etc. I have a CSR electric water pump, big Griffen alum. radiator and 22" electric fan (no shroud). Car seems to be running around 185-200 deg F depending on ambient temp. Getting some "blow off" into the overflow- seems premature to me and I'm thinking the radiator cap may not have high enough lbs rating.

What are you guys running for a cap (lbs)?
Any other thoughts?

Thanks in advance for your responses!
 

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Drag Week Survivor
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At 180-200 degrees your not going to boil the water, so you don't need a high pressure cap to raise the boiling point... Make your tank so it will be a recovery type tank and keep a little in it when it's cold. anything that gets pushed out, will get sucked back in as the engine cools. this of course is true if you completely bleed the system to remove all air, and your recovery tank isn't mounted to low.

I like the lowest cap possible to keep the pressure low to prevent hoses and gaskets from leaking or potentially blowing out... The only function of a high pressure cap is to raise the boiling point.
 

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Discussion Starter #3
Very helpful input! Thanks for the quick response too.

My overflow is mounted on my motor plate, lower than my cap which is actually on the thermostat housing (no thermostat) not the radiator (radiator has not cap and is mounted lower than the filler neck). That being said, and along with you advise of a recovery type overflow, how exactly do I accomplish this? Can I buy a tank specifically made for this purpose? Should it be mounted level with the cap, above or slightly below? Some guys run the overflow at the back of the car...will this work also with recovery type overflow or not.

Also, how can I ensure all air has been bleed from the system?

Once again, thank so much for your input/knowlegdge!
 

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T/S 368E
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.

I was taught to use a higher cap.
I've been using a 28-30 for years and never blew out anything.
I don't know all the details, but the 2 guys that told me to use it are beyond reproach.
Including being a retired P/S guy. You shouldn't have anything that fragile that it could pop.

.
 

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Discussion Starter #5
Thanks for the input...yet another perspective.

P.S. Nice ride!
 

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RED ROCKET
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i use a 22 or 24lb cap on my stuff.
 

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Discussion Starter #8
Thanks to everyone for all your input.

I'm confident I will resolve this problem thanks to your experience/help!
 
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