Just as an FYI (from a lesson I learned last week).

I installed a ProComp Air Gap Intake on my 455 and torqued it to 25 ft/lbs. The engine ran for a total of approximately 10 minutes (a few short runs and an approximate 5-minute run). After this the intake had a slight water leak on the driver's side front where the intake meets the head. The first thing that I did was to re-torque the intake to 25 ft/lbs again (Motors calls for 25 to 35 ft/lbs and, since the intake is aluminum, I figured the the low end of the torque spec was a good place to start. My intention was to torque it to 35 ft/lbs after it started leaking; however, you would not believe how loose that intake got after running the engine for only 10 or so minutes! Most bolts, including the one near the leak, rotated about a half of turn.

All is good now.

 

when you torqued them the first time, did you go around the sequence a second time after it was torqued at 25? if you took it to torque and didn't go around again that could be the reason they were loose. the first ones to torque on the intake will loosen up as the others are tightened. i have had to go around 3 times before when using the valley pan gasket.

 

Good point but I'm pretty sure that I checked it at least one time after torquing.