What bit and tap for the oil return on a 4.1 block??

[rking]

Ive done a search and have come up with 2 answers to the question:

What bit size and tap do I need for the oil return on a 4.1 block??

1. 23/32 1/2 - 14 npt
2. 29/32 3/4 - 14 npt

Pretty big difference between the two, just hoping that someone has experience with this and has done it. Let me know, Thanks!!

 

[boostingbuick]

1/2 npt is the correct size.

 

[Dwayne]

1/2" npt is correct..........takes a 23/32" drill bit.......here's a handy chart for future reference Tap Drill Sizes


When drilling a 4.1, you will be close to a rib in the block. Be sure and leave yourself enough room for the head of the fitting to spin without hitting the rib...........or just dump the oil in the front of the oil pan.....good luck.

 

[49-blues]

I used the 1/2" npt-fit perfect.

 

[rking]

I appreciate it guys!