tonight i tried to fill the cavities with JB weld. It was very messy. The two cavities connect and I had JB weld running out. After taping off one side, it went well. It is hard to tell by the pictures but the cavities you see are on a totally different level than the actual intake runners. I am a little nervous about the temp getting too high, but JB Weld says its good for up to 600deg. So, we'll see.
One thing to do before you put in the JB Weld, is to use a mig welder in the areas you are applying the JB Weld,, using a mig welder let the wire weld to the intake & leave the wire in the welded areas & cut off the too long of wire,then apply the JB Weld,,, this will allow the JB to grab onto something ( the wire ) & not break loose & possibly go into your engine.
Hope that makes some sort of sense?
12 port SDS EFI