So I'm doing a little project with meth injection and I'm wondering on a tapped 1/8 npt hole, how many threads should be contacting the fitting being screwed in? The hole is tapped in about 1/8 of material so it has about 4 threads after tapping. Fitting turns a few and gets right like it should. Is 4 threads enough u think or should I try to weld a bung on, this is cast aluminum so I don't know how well welding a bung will work

 

If you can get a nut on the side through the pipe it will hold it much better. Sort of jam nut it into the pipe

 

Teflon tape

 

I don't think a nut inside the manifold would be a good idea lol. And no Teflon tape, e6000 sealant. Meth proof

 

All I need to know is if 4 threads is enough for a good hold, sealing it is no problem

 

T-tape is meth proof also.

The nut on the inside is to hold the fitting into the mani. If your material is only 1/8" thick there is a good chance you'll blow it out

 

I'd rather do a bung in that case. Be safer, I'd just be paranoid the but would fall off , plus if I ever wanna change nozzles if have to take off the manifold, that's just not practical

 

4 threads should be fine. See this https://www.pegasusautoracing.com/do...ocID=TECH00097

 

That's what I wanted . Then I should be good. Good stuff. Thanks

 

4 threads leaked on my lower charge pipe.

 

1.5 to 3 turns past hand tight? Torque is a big factor.

 

Leaking threads is lack of proper sealant. Iv had more threads than that leak till I used a good sealant and a decent amount. E6000 has worked the best for me

 

4 threads sounds fine to me

 

I just checked the nozzle and they only have 6 threads, and ur not supposed to bottom a npt fitting out or it defeats the purpose. so 3 or 4 threads holding seems fine to me.

 

The rule of thumb is 1/2 bolt diameter in thread engagement for maximum strength. The issue with NPT is it is an expanding thread and you have to be very careful threading it in too much. We made a meth fitting threaded into the runner in a stock LNF manifold for Cory ( R3volution) on here, I have some pictures someplace , it appears to be holding up but it is a fragile deal no doubt.

 

So that would be just the right amount on the intake
Without using a bung. If it ever pops out I'll just simply weld in some bungs. I doubt it will though, I know my charge pipe nozzle is screwed in about 3 or 4 threads and that's held for a good while. And that e6000 sealant is like glue. So Ill be good. Fun project