Engine Coolant Passage Pressure Testing

[Lefty71]

So, I'm wrapping a 383 build with some '915 heads and I wanted to pressure check, especially since this is a mix of parts never together before. I put my test on, and started to question what I should go to?? I figured 20# or so would be more than the cooling system would ever dish out, but then started thinking, well the head gasket should hold a heck of a lot more with the job at hand, and the iron could certainly go much higher, so what do you guys think??

My heart sank quick when I could not hold pressure, but it was just the exhaust bolts. I tried some copper sealing washers, so I didn't have to goop anything til header install;

But I still got this;

Now I'm waiting on goop to dry to try again..

 

[snakeoil24]

6-12 psi

 

[steve340]

I would only bother to go to the radiator cap pressure.
16 to 18 max.