Report Anybody use Northstar Performance? in Cadillac Deville, Eldorado, Seville, Fleetwood, Sixty Special Posted November 13 You can't go wrong with Cadillac's recommendation, Timeserts and new studs from GM. As you note, the GM studs are torque-and-twist. This method uses long studs from the head to the bottom of the head bolt well in the block as a tension spring, and keeps head clamping force within bounds as the bock heats up and cools down. Torque-and-twist is a time-honored method for reliable had studs on aluminum engines of all makes. Using steel bolts that are too wide to stretch as the block heats and cools is well-known to result in too-high clamping forces if the engine overheats. If you end up pulling the engine again for further repairs, see if you can get the recommended Timeserts for your engine installed.