radiator pressure cap

I just installed a aluminum radiator in my 57 chevy, what pressure cap do I use? I have a 160 thermostat and only use the car in the summer, if that matters. thanks for any help.  

why did u put a 160 therm, in it ?  i put a 195 in mine w, a flex fan and the thing does fantastic, even on the hottest of day,s, w, 400 hp!  

the original radiator in those had a huge top tank...  so a 7 or 13 pound cap would be max...  to prevent radiator damage...

i take that it's a welded aluminum crossflow radiator... so 13 or 16 pound is good... you are planning on running a coolant recovery bottle...  so the coolant can expand .. push past the radiator cap  as it warms up... when it cools off.. it contracts and pulls the coolant back into the radiator... keeping the radiator full all the time...   making the most of the cross flow design..

there are several options available in the speed shop catalogs..   there is one option that might be hard to find ... 75 volvo 164's had an external coolant expansion tank.. with a conventional radiator cap on top.. and a 8mm fitting on the bottom.. it also is tubular...  it did not hook up to the overflow on the radiator cap.. it hooked to an elbow on the top of the radiator.. so it held the pressure and kept the radiator full to the very top...  if you squeezed the top hose a bunch of times... you could work all the air out of the cooling system to make it work even better..

there was something discussed a long time ago.. in probably PHR about project X...  the large top tanks when run without a thermostat had enough surface area that when the engine was revved really high..  the water pump had so much flow that it would build up pressure in the top tank, it would expand the top tank until it broke the solder joints...  i even remember the issue where project X was brought out of the orchard where it was stored...