I just finished tapping the exhaust manifold..took my time...took me roughly 30 minutes just because I did not want to mess it up, here is my question, I can get the nut pretty tight, but one thread below the hex part where you grip it with the wrench is still visible...is this acceptable? It tightens perfectly, and my worry is that if I keep tapping it wider, that the nut will bottom ont he manifold before proper torque is achieved, so me thinks it should be pretty good. I also took ya'lls advice and got real good drill bits, cobalt, and drilled a 3/16" pilot, then a 7/16" final, even worked with my crappy 9.6 volt cordless that was charged 3 months ago. For some reason the handle I got did not work with the tap, so I used a set of vice grips with the tap..and ALOT of cutting fluid.

Your depth is OK on the pipe threads.





How was the chip formation during tapping?

I hardly saw any chips during tapping, I could however feel them break when I backed the tap up every quarter turn, and the nut goes into the manifold very easily, and tightens very well, I think i scored a decent tap.

Your depth is perfect. If you go too much further, it will bottom out and you will not be able to get a nice tight seal. Don't forget to put some anti-sieze on the fitting....
Bob

Bob's right about the anti-sieze, high temp nickel stuff if you've got it, but anything is better than none.

I did not use any antisieze..why exactly is it needed?

I put it on mine. Just in case I need to remove the fitting. 70,000 miles and haven't had that need. Nothing wrong with a little forward thinking in all you do.