No, don't trust the JB at that point in the manifold.  I have been porting for 49 years, used JB Weld in lots of intake manifolds, but in areas where you can stake the pour, or pin it.  If you can stuff clean rags into the intake and vacuum it afterwards, you might create a groove in each end of the slot and make a corresponding but opposite groove in the piece you intend to install in the slot.  Drill through the new piece down into the manifold, and stake that, then add JB Weld, it would be acceptable.  Blend, vacuum the area diligently, and remove the rags while using the vacuum to make sure nothing enters the engine.  It depends on how diligent you are in the modification if I would sanction it.  I have JB Weld that has been in a pair of SBF aluminum heads for nearly 30 years.  The other option is using Splash Zone A & B, A-788.  Easier to work with, but still needs the same prep work to ensure the added piece does not get injested in the engine.  Joe-JDC

JDC

I'm in agreement with Joe.  That would be a NO on trying to glue something in that opening.  That piece coming out at a later date can prove to be catastrophic.  What Doug did with the V’s cut in both the divider and the fitted piece for the opening gives the added piece some real support and is there for the long haul.  What Charlie did in having the slot welded shut is the ultimate fix.

Another option besides the two aforementioned methods would be to machine a 1” aluminum spacer so the spacer is approximately a quarter inch thick but leaving a protrusion sticking up that matches the slot in the plenum divider.  That would allow the slot in the divider to be ‘filled in’ while not having to remove the manifold.  If using a 2” spacer and machining it just enough to leave the same aforementioned protrusion, then you would have a taller spacer.

But manifold removal on the Y is reasonably straight forward as the distributor does not need to be removed to do so.  Regardless of the method used to fill in the slot, eliminating any potential gaps in that opening gives the best results.

Lorena, Texas (South of Waco)

I haven’t heard the words “Splash Zone” in years. That was the best epoxy I every used in the power plant industry. It was indestructible and could live in anywhere we put it. Worked with any fuel and could be applied underwater. 

56 Vic, B'Ville 200 MPH Club Member, So Cal.