I am Installing a aluminum intake on my 390
Do I need the valley pan or will it be fine with out it

 

You need it, it's a critical part..

That being said, the intakes can be tricky to get to seal without leaking. Make sure you follow the torque spec and sequence properly (It might be different with aluminium).

 

The valley pan will keep hot oil from splashing all over the bottom of the intake and since your new intake is aluminum will be even more so important.

 

It was engineered with a valley pan.. must be important, right?

Dimple the China walls so the RTV has "feet" to grab hold of.

... and before torqueing down the intake (like 25 ft.lbs. IIRC), align it by installing and seating the distributor.

 

You might want to call the tech line on your intake and check with them.