390 oil pressure & cracked exhaust manifold

[wyngnut55]

Newly rebuilt 390, 250 miles on it now. Cold oil pressure at idle 40 psi. Hot oil pressure at idle in gear 10 psi. 10w30 oil. Higher rpms pressure comes right up, freeway speeds around 40 psi. Is this normal idle oil pressure on a total rebuild? Should I be worried? Seems low.
Also I have a vertical crack about 2" long about mid/outside of driver side exhaust manifold. Anyone repair a cracked manifold with any luck? Brazing rod?

Reading past forum posts now, the oil pressure question looks like its pretty common and talked about quite a bit.

[Busboy]

I would prefer it to be a little higher at hot idle but I don't think it will damage anything. I'd look for a used manifold but they have been successfully repaired in a number of ways. Might as well give it a try.

[Ranchero50]

Oil pressure is about normal if you installed a standard pump. I do high volume ones and it makes a huge difference at idle without hurting it too much up top.

I'd just replace the manifold. You'll add stresses welding it up so it probably won't line up well once done.