I recently tore down my 350 for a top end job and one of the things I found was that a large section of the intake gasket was sucked down into the lifter valley, it looked like it just sagged down in there. I was trying to figure out what might have caused that and the only thing I could come up with was that maybe there was a problem with the PCV system and it created a vaccum in the crankcase sucking the gasket in.
Anyone have any other ideas on that?

 

Pretty hard to get a greater vacuum in the crankcase that way. You can't very well take a little bit vacuum out of the intake through a skinny pipe with a piddle valve in it, put it into a big leaky crankcase with a vent in the side of it (in the other valve cover), and come out with more vacuum in the crankcase than what you started with in the intake. It just doesn't happen that way.

It was a faulty installation for whatever reason, pure and simple. The usual cause is a combination of a slightly bent intake gasket (bent upwards), and not setting the intake down centered; that allows the bottom of the runners that end up being the "high side" to catch the bottom of the gasket runners.

I usually tape the center of the gasket to the head, in that big clear space between the exhaust and intake ports, with clear cellophane box tape, to avoid such catastrophes.

 

It's almost as hard to believe that someone would botch up an installation that way, as the vaccum sucking it down. But I think you're right about that RB. It may have been a cheapo casket that had a lot of 'bendyness' to it that contributed to the problem.

Thanks for your opinion, Later