I have never tpped anything before, how do you know when to stop, turning, how deep do you go, and when drilling and tapping, will a nice spray lubricant work for colling the bit and tap down?

 

Lots of questions. most taps depending on who you use, you'll go in untill the last few teeth show, normally 4 on a NPT tap. If your using a normal tap go in as far as you want the threads deep. If your taping for a pryo gauge it's a NPT tap and you will first drill the hole (use lube here also this creates lots of heat) then start taping. On the manifold of the dodge, most use grease to trap the shavings in them and is a great lubricant. Most Taps done by hand won't get that hot so really your lubricating the cutting teeth more than for heat. We also use Tapping fluid (not sure of the brand cause it's in a FDA bottle) but works good. Take your time and check the depth (pull tap out, clean threads out, thread in piece you want, see how much it goes in) you'll want at least half of the threads to be able to go into the hole you just tapped. Sorry this isn't more technical, but it's early and I'm still waking up.

 

You will typically need to run a NPT tap in until you reach 5-7 threads from the smooth body of the tap (this also depends on tap brand, some cheap imports don't follow this standard). To check thread depth, the fitting should turn by hand 3 threads (called hand engagement). Run the fitting in by hand until it stops, then back the fitting out counting turns until the fitting releases from the hole.

As far as lube, drilling gray iron with a hand drill can be done easy enough dry. But, using grease to catch chips will add all the lubricity you'll need.

 

If you've never tapped something before, I highly recommend tapping a test hole in something other than your exhaust manifold. Maybe an old piece of steel or something.

Nothing wastes a day as quickly as a broken tap in a valuable part.

 

Make sure you have the proper size drill bit for your tap.

 

Truer words were never spoken