[mgarblik]

Originally Posted by 63Banshee

Block deck has huge influence on head stability and subsequently head gasket survival.

The block is important certainly, but don't forget the head bolted down to it. Case in point: Our very tall and stiff billet head has survived at 3000+ HP on both aluminum and iron IA II's for 8 years on one pair of head gaskets. No compression leak witness marks. That's with the stock 10 head bolt layout that everyone said could never be done. Clamp load is what it's all about. 9/16" studs torqued to 135 PSI. A solid head with lots of meat around every head bolt column. Use a light, flimsy aluminum head on an iron block with long, wimpy 1/2" studs at 95 ft. lbs and all you get is 10 pulled-up areas around each head stud and leaks all around, especially where the heat concentration is in the paired exhaust ports. Above 1000 HP, your asking allot of the head gasket IMO. Bore spacing doesn't help, but I am not convinced 4.840, or even 5.00" alone is an instant cure.