Drilling and Tapping Guide for Exhaust System

When replacing the transmission in my truck, I took the opportunity to fix a bad exhaust leak on the driver's side. Like many of these Chrysler LA engines, my 2000 V6 Magnum with 170k miles broke 2 of the 4 exhaust manifold studs.

The two rear ones (the ones with the least access) were damaged, and I wanted to provide a guide that would enhance the chances of drilling and tapping these holes accurately.

My initial foolish attempt involved drilling the center of the broken stud and using a helical bolt extractor, which snapped off in the hole, creating an even bigger mess. I drilled it out with cobalt bits and decided to enlarge the hole and re-tap it. Unfortunately, the cheap tap I had also broke. I mistakenly used a plug tap instead of a bottoming tap, which caused the tapered end to hit the back of the hole and halt progress, resulting in a snap. After two more breaks, I used this guide to ensure I could drill and tap straight.

I designed this flange using the exhaust manifold gasket as a reference. Since the V6 is simply a V8 with two cylinders chopped off, parts like the gaskets are essentially just cut-down V8 components. Thus, the guide may seem to not fit well with the head, but it works fine and, most importantly, the bolt holes align. This design is very specific, likely to be unnecessary for anyone else, but I enjoy sharing it to balance out the many great designs I have used over the years.