To be honest, if you are going to be pushing the envelope with a stock block, the main/valley girdle is only gonna keep your parts in order when they explode, they dont stiffen up the block enough straight simple. Trust me!

 

I see a lot of people make this mistake, bottom line if you are pushing the limits of a stock block you need to go an aftermarket block. Filling a block to me is for race only, don't even drive the car for fun. If you think buying an aftermarket block is expensive, compare that to the cost of wiping out your stock block/internals when it splits and redoing your engine AGAIN. I'm not a rich guy, if I save I can build something right the first time and not worry if I want to take it to the track. As far as girdles go, think of why women wore girdles years ago...yep you got it, to make themselves look slimmer then they actually were, so when your block splits, you will have two very nice and neat 2.5L 4 cylinders.