Im not sure I understand your head return line system resevoir 7# cap system. Whats your cap psi on the rad?
Yes, all cars are required to have a overflow can. Ive got one too.
A boil over is a violent event in terms of pressure. Preventing this with a stronger psi cap from the get go is a good idea adding extra safety insurance.
Once a boil over occurs the Vapor pressures skyrocket. Prevent that boil over with a few extra pounds at the cap . Priceless
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My pics are too large to post but I have 2 lines
coming from a manifold on each head to a box/reservoir
with a cap on the box... the radiator has a 15# but
the reservoir has a 7# that is the low pressure
point of my system (remember I run W-9 heads so
they are different than most heads)
