Threads on the Intake Manifold on a 71 (1 Viewer)

[Tacoman99]

Hi

I am replacing a cracked intake manifold. It has a couple of fittings threaded into it. The replacement manifold had the fittings removed and I was just going to replace them. The fittings in the old one are really stuck. Fittings with NPT threads don't quite fit and I suspect they are BPS. Could someone confirm that these really are BPS threads?

Also can BPS internal threads be retreaded to NPT? I believe they can since the thread pitch is the same and only the profile differs. Has anyone successfully tried this? My questions is; Will it seal.

Thanks for the help.

 

[georgia fj40]

Npt is tapered. Britsh standard is straight I beleive. 3/8" npt will thread right into M18 1.5 like drain and fill plugs on t case and trans. I used 3/8"npt by 90degree 1/2"jic. for a bypass hose but really no pressure. Have read multiple people that swear 1/4"npt plugs work perfect for smog air rail removal. Im fairly certain threads are not bsp but metric. mcmaster car sells metric pipe fittings.

 

[Tacoman99]

I know the BPS is also tapered. The small holes on manifold are tapered and the 1/8" NPT will go in a couple of threads and then bind. I went back and checked the specs. The BPS is 28 tpi and the NPT is 27. My bad. The tread count on the manifold is 28 so I am betting it is BPS. I have not run into a metric pipe threads, they must exist. I have seen BPS on Japanese cars that were otherwise all metric (Nissan, Pathfinder). I may have wasted too many scarce brain cells on the issue. I will probably should get some Liquid wrench, a torch, and make a determined try to remove the fittings from the old manifold.

 

[thebigredrocker]

Stumbled across this thread while looking for confirmation the 3 bolts that sandwich a 71 F manifold are 1.25 thread pitch.

Figured I should make a slight correction to this thread and mention the manifold vacuum threads are called British Standard Pipe Tapered(BSPT) 1/8" for the vacuum transfer shift hose and 1/4" for the brake booster hose. Aisan carb also 1/8" BSPT. Kyosan-Denki and Nikki fuel pumps also 1/8" BSPT.

When ordering fittings listed as BSP make sure it's the tapered version not the parallel version. BSPP fittings are parallel.

I am a about 51% sure the only BSPP fitting on my 71 FJ40 was the threaded nipple on the fuel tank. 1/8" BSPP male.

 

[thebigredrocker]

Anyone know the thread pitch of the long through bolt and the 2 shorter bolts that clamp the Intake/exhaust manifold together? On a 71 FJ40
@73FJ40

 

[73FJ40]

Anyone know the thread pitch of the long through bolt and the 2 shorter bolts that clamp the Intake/exhaust manifold together? On a 71 FJ40
@73FJ40

I'll have to double check later today.

I believe the OEM ones are still available.

91111-51090 for the long one and 91111-51025 for the two short ones. Also 94512-01000 for lock washers.

 

[73FJ40]

I'll have to double check later today.

I believe the OEM ones are still available.

91111-51090 for the long one and 91111-51025 for the two short ones. Also 94512-01000 for lock washers.

Confirmed: M10 x 1.25