Use a 1/4"x18 NPT Tap and very carefully tap your hole. I used an 11mm wrench to turn the tap. Make sure you line your tap up correctly. Use cutting oil or WD40 and slowly begin to tap your threads. You will need to go about 1/2 down the tap and insert the Monster Valve to check the depth. Remove and continue to tap until you have reached the correct length. DONT GO TO FAR! These taps have a taper and you could open the hole up to much!
Once finished you will have a cleanly tapped hole
test fit the Monster Valve
Remove the brass end cap and the red release nut. Use a 9/16" deep well socket to thread the valve into the rim.
verify the depth
remove and apply thread sealant
reinstall the Monster Valve using the 9/16" socket and thread the red release cap back onto the valve
thread on the brass end cap
The finished product. As you can see I placed the Monster Valve directly across from the valve stem. This gives you enough room to place a gauge on the valve stem and air up or down using the Monster Valve.
Reinstall the ring, let the thread sealant stand for at least 15 minutes (I let my set up overnight) and air up!
could you or could you not tap the original vale steam hole?
You could if you drilled it to a 7/16" side and then tap to the right threads. But the whole intent is to place a clip on gauge on one and air up or down thru the monster valve so you can monitor it as you do.