EEC-IV question, ACT thread size

**My427stang** · 09-20-2009, 05:45 PM

Does anyone know the thread size of the ACT (IAT) for a 90's Mustang? Its close to 3/8 NPT but it uses an o-ring to seal, so it seems like its straight thread.

I measured .655 diameter and 4 threads per .2 inches (20 per inch) but it doesn't seem to match anything. It is smaller than O2 sensor threads.

Thanks

**FEandGoingBroke** · 09-20-2009, 09:00 PM

you mean the threads for the two Torx head screws?

I believe they're 6mm X 1.0 pitch.

**My427stang** · 09-21-2009, 04:01 AM

No, I mean the thread size for this

It looks like pipe thread, but it seals at the top with an o-ring, pipe thread is generally tapered and you don't bottom it all the way out

**pass1over** · 09-21-2009, 07:17 AM

i used a 3/8 npt tap and it threaded right in, grey permatex the threads and gtg

**gbic1** · 09-21-2009, 08:09 AM

Not supposed to be O ring there. I was at the dealer when fuel injection came out till late 90s and Ford never use O ring just pipe dope.

**FEandGoingBroke** · 09-21-2009, 09:18 AM

Get some pipe threads and test it by hand, but 4 threads per .2" is 16 threads per inch which isn't pipe thread and it puts you just under 11/16" which is nearly spot on for a 17mm by 1.25...

It's not pipe threads....

Remember if it's a two pin connection the body of the unit needs to be grounded in order to function properly before putting any kind of sealer on it that might cause a poor ground between it and the manifold. That signal needs reference points and the ground is one if them.

3 wire connections usually carry the ground from the ECM with them so sealant isn't a bother.

**stvrrr** · 11-14-2009, 05:17 PM

3/8 NPT.. I just tapped my Explorer intake for one. Fits like it should!