dual electric fan mounting question ?

I can actually put the fans side by side. If i use the shroud mounts it will give only 1/4 inch between the rad and the aluminium cover that I'll mount the fans to, witch will mount with about a1/4 inch spacing. Also the aluminium sheet is about 1/8 inch thick (like stop sign material). I'm wondering if the 1/4 inch between the rad and the aluminium sheet will be enough ?