Stripped Holes in Cylinder Head for Intake Manifold Bolts

Unless you have "64" or "65" 273 or magnum heads, they are Not at a right angle to the surface. Thanks Volaredon and Badlittlered. I measured them about 8 degrees so probably between 7 and 9 degrees is correct, but I do not know the theoretical correct angle. 3/8-16 thread. Or use Timeserts. Use a torque wrench, a beam type.

https://www.timesert.com/index.html