Cylinder Head Plug

[vinman1369]

Picked up 4.0L cylinder heads off of ebay from carolina4wd.com for my 99 D2. The item description said "These are the newer style for lower emissions. A brass plug will be needed on each side to fit to a Discovery I or earlier P38A Range Rover" so I figured I was OK. It ends up that I will need this brass plug. I know it is 3/8", but does anyone know what thread style it is? I have tried NPT, NPTF & BSPT. None have fit, the thread seems finer. Please help....

 

[D Chapman]

Can't remember the size rigth off, but it was a fucked up metric thread - could not find it anywhere! I ended up welding the holes shut.

 

[frickjp]

The hole is 5/8" x 20TPI. It's an odd size. I have a set of the SAI fittings that go into those ports, if you can't find plugs, you could get the holes in these welded up and thread them in.