Torque specs
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
3/8"-16, Grade 3 [intake manifold] bolts get 28-32 ft-lbs. but should be torqued in a specific pattern and should be stepped up to get to final torque. I.e., follow pattern and set to 15 ft-lbs; repeat pattern at 25 ft-lbs.; final round at 30 ft-lbs. Doing so prevents crushing the gasket under the first few bolts that get torqued and allows the gasket to take an even set. You should do one more 'round' of torque at the 30 ft-lb level after about 30 days of vehicle operation after that installation. Check the Chevrolet Chassis Service Manual for the torque pattern.
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
Just be advised, these old aluminum intake manifolds are easy to break. I would stay on the light side of torque specs, just to be safe. Which would you rather possibly have, a manifold leak or a broken manifold?
