Maybe I will pick up a single tap. I actually have a 7/16 tap, but its the 20 pitch. I read that a 1/4 pipe thread has a 18 pitch thread.
I wanted to avoid pounding on the manifold to get those freeze plugs in. At least with a tap & screw-in plug, there will be less (?) forces applied to the manifold and its gaskets.
When I replaced my intake gaskets, I also installed GMs valley baffle. I had to follow up and retorque the intake manifold 5 times since then. After I install the plugs, I think I will recheck the torque on the manifold bolts, just to be safe.
While I'm on the subject, I used to have an oil consumption problem with my truck, but after replacing the gaskets and retorqing several times, it eliminated the oil consumption. So I strongly recommend to anyone working on their intake manifold to retorque those things several times. Those Hot & Cold cycles really affect the gaskets and settle the manifold.
