Head gasket question... trimming drain hole?

[Desert Stallion]

So I get to change head gaskets on my sister's '95 coupe... again... but my question is: Why have I been told that you need to trim a 'drain hole' in the updated gaskets when using them on the '95?

Last time I did this 6 months ago, I know I didn't know to trim a hole, but I also used just your basic FelPro perma-blue or perma-seal gaskets, whatever was in their head-set, along with new FelPro head bolts, and the b*tch sprung a leak after only 6 months and maybe 6-8 thousand miles.

Was it an error on my part... maybe, but I've done many many head gaskets in my time, and I've NEVER had one fail before (minus on a blown 10-second GT, but that's a different story having to do with mixing forced induction and nitrous). Did I miss something, maybe. Was it due to damage to the heads that I didn't see? Maybe. Was it because I didn't trim this 'drain hole' in the gaskets? Well, since I didn't know anything about it, I guess it certainly could've been.

Thanks all.

 

[Stangfanatic98]

I'm not sure about the drain hole (never done it before). But i'd make sure you get the heads machined so that if they were warped for some reason you won't have as big of a chance for a leak later on down the road. Unless you already had that done...