barb fitting / nipple on back of manifold

[catch2nd]

I am building a vac manifold and I was going to feed it with the small barb fitting of the back on the manifold that faces the firewall (ya know, the one that always gets broken when you pull the engine!!!)

Basically, the nippple is real small on that, so I wanted to replace it with a large i/d fitting and I wanted to confirm the thread size, i did some searching and it looks like its 1/8" pipe, can anyone confirm this?? I figured it would be a metric pipe thread but I read it was normal 1/8" NPT that I can find at the hardware store?

Thanks guys,
Dustin

 

[supra90turbo]

Why not bring the fitting to a store with you?
That said, I don't know what the thread is, so.. that's what i would do...

 

[catch2nd]

Why not bring the fitting to a store with you?
That said, I don't know what the thread is, so.. that's what i would do...

They were closed, and I had a 1/8 NPT barb in hand that I wanted to try...

I did a little more investigating, it seems more reasonable that the fitting is 1/8 BPS (british pipe thread) aka metric pipe thread. The had a 1 thread per inch difference as well as the NPT having a slightly larger overall diameter... I compared the fitting and you cannot see a difference in TPI, however the dial calipers show the supra fitting to have a smaller diamter. I attempted to thread the NPT fitting in the manifold, it actually goes in a few threads and then starts to tighten!!!

 

[lagged]

dont forget the big one on the front facing side of the intake manifold.

 

[supra90turbo]

dont forget the big one on the front facing side of the intake manifold.

That's the one I was going to use on my mani, but now with my decision of FFI, I'll just have a similar size tapped in on the rear of the mani.
catch2nd: you should use a decent sized supply since you're feeding a lot of other things off the manifold, you don't want to choke it down with a 1/8" line for a feed...

 

[catch2nd]

well an 1/8" pipe thread is actually a 1/4 ID barb, do you think that is large enough??