Oil pressure gauge thread size???

[Jaysonb]

Some how the copper line for the factory oil pressure gauge got lost while I have had the truck tore down. The truck is a 77, not sure if it's 1/8 npt??? Any help would be great.

[Jake Wade]

1/8 NPT is correct for the location by the distributor

[ray_mcavoy]

Yes, like Jake said, the oil pressure port on the block is usually 1/8" NPT.

The back of most factory GM mechanical oil gauges take a special type of compression fitting that has the ferrule built into the nut. Weatherhead calls them "threaded sleeve" fittings and Edelmann calls them "double compression" fittings. The nuts (with the built-in ferrules) that fit 1/8" OD tubing are Weatherhead #6100x2 or Edelmann #111200.

The factory oil line used those special compression nuts on both ends of the line. On the engine side it screwed into a male pipe adapter that threads into the 1/8" NPT port in the engine. Replacement adapters are available as Weatherhead #6200x2 or Edelmann #112220. However, they are a bit shorter than the factory adapters used on small block V8's and might make it harder to reach down behind the intake to connect the oil line.

Here is a post by LockDoc with some photos of these fittings --> http://67-72chevytrucks.com/vboard/s...d.php?t=613238

[Jaysonb]

Thanks Ray, that is exactly the info I need!