What is the function of that steel plate other than to have the gasket fail and cause you constant problems? I know you can replace it with an aluminum plate so my question is why not just weld and aluminum plate over the opening and be done with it? What am I missing here? Thanks.
Ken

It had to be there to make the casting I think.

Aluminum is a bad choice as it will conduct more cam oil heat into an already heat soaked desighn.

I like sealing them with right stuff on either side of the gasket, it is a little flexible and very strong and since Al and Steel expand and contract at different rates it needs to be able to move, the gasket alone won't last long in that environment.

Also just welding on a flat plate will reduce hp by moving the floor of the plenum closer to the mouth of the ports, the steel pan has a step to help aleviate some of that.

If its just an old piece of junk you dont care about and you have some sheet Al laying around you don't mind wasting then by all means weld away. You will want to make sure it is thick enough it wont flex and fatiuge and crack, 18" vacuume over that big of a surface is a pretty powerfull force to be going on and off constantly.

The large bottom hole was to get the sand from casting out.
The center divider inside the intake manifold makes this harder.

Two, even three, round threaded holes on the bottom without gaskets would have been better considering the large scale problem with all the fix-it labor cost that has been expended.

A V8 version of the V10 manifold would have been a far superior towing improver.

Ok, thanks guys, that does get my brain to clickin.