NPT question
 

I have a oil leak down at my oil filter adapter that routes the oil from the bottom of my BBC (Dart) up to my remote housing. I isolated the leak to what I think is 1/2" npt coming out of the adapter to -10 an going up to the remote housing. When I pulled the fitting out it apeared not to be standard tapered pipe thread it was straight thread and shorter with a oring. I bought a fitting with 1/2" npt which threaded in nicely but was very sloppy on thread lash and would definately not hold oil pressure. My question is what is the proper fitting to go in, is it surpposed to be a oring seal or is it tapered npt? All the ones I find online like at CP performance mention 1/2" or 3/4" npt? I don't know what to think. I would just take the whole assembily to the parts store if I could be as you know it is in a very akward posistion and removeal is next to impossible without tearing half the motor apart. The motors are 532ci Dart blocks 871s 850hp

When you said that the 1/2 NPT fitting threaded in but was sloppy - was the fitting bottomed out ? ( no threads showing )
If it was then it isn't a NPT thread.
What does the O ring look like? Any cuts of abrasions?
I would say put a new O ring on it and some locking thread sealer up by the O ring only and tighten it back up.

I didn't bottom it out, it just didn't seem to be snugging up as I threaded it in. I will get back in and try it again. I am begining to think it isn't NPT.

port thread
 

if the fitting has a o-ring on it . that is a straight thread size #10
that is a 7/8-14 thread. if you screwed in a 1/2-14 npt pipe it will fall out. look at the port that you are threading in to if it is a straight thread port you will see a chanfer for the o-ring to seat in to. if you have a small drip you may have a bad o-ring.

If you could lower a digital camera down and snap a pic of the port we would be more helpful.