What size NPT is the vacuum tree fitting on underside of manifold??

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
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I'm setting up an Explorer intake to work on a Mustang. I want to remove the brake booster line and thread that port to accept that black vacuum fitting that comes on the Mustang HO intake. It's the fitting that the booster, EGR and FPR vacuum lines plug into.

Anyone know? Is that 3/8" NPT?
 
The fitting on the intake on the left is what I mean



My explorer intake is like the one on the right. Trying to make it Mustang friendly
 

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i think thats just a stashed image for reference, what hes looking for is the vacuum log on the left side of the middle plenum hump.

i havent messed the with explorer intake i have here, and its been a while, but i think all those fittings are 1/8" or 1/4" npt, depending on location. for those that dont know, npt sizes are a bit confusing because its not describing the outside of the thread like a normal bolt, but the inside of the intended pipe.
 

NPT also tapers as it goes in. The outboard threads would be a larger diameter than the inboard threads. You could also measure a different diameter for the same size depending on how deep the tap is run in.
 
I don't have the fitting. That's the problem. I need to find one, but I have the tap set handy now along with drill bits. I just don't know what size


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Then you are SO set! The difference is easy to see using the different taps. Tapered NPT (yes, I know how to fit a pipe and fiting together too - and I prefer teflon to being or using a pipe dope 99% of the time,) or not. The bit will measure the small end of the hole or what you want to tap, and the taps will measure the hole and compare to the (missing in your case) existing fittings too.
 
Yeah, I'm not too worried. I gotta see if the stock HO intake I have in my basement has the fitting (doubt it) or ill have to snag one off eBay or something.

Just trying to get it tapped while I have the tools out.

Here's the actual intake.


As you can see, I yanked out all the vacuum tube fittings except the booster fitting. However, this is where I'll tap for the Mustang vacuum fitting so it will come out too.


Left hole getting plugged.


Small port will get a fitting for the vacuum canister, and I'll be plugging the big hole on the plenum.

Then some aircraft stripper, chop this nub off the plenum and hot tank it


Then who knows what finish I'll use.


BTW, I already have a real ford 1993 Cobra intake. This is just a side project because I can't sell this damn thing so might as well mAke a cool wall hanger (that could be used) with a 5.0 HO intake plate. The lower intake will be ported and swapped at some point on my car


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I found the spare manifold (with the part missing) with the good hole to measure. My NPT taps are MIA. But my 1/4" air line fittings fall in, and the hole measures .590" at the deepest the caliper reaches. It looks (from the chart) and feels like 3/8" pipe to me.
 
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Thanks man. I had a feeling it was 3/8npt. I've got the drill and tap all set to go.
 
Thanks man. I had a feeling it was 3/8npt. I've got the drill and tap all set to go.
I know this topic is quite old, but one question. If you drill and make the thread in the existing hole, does it work to put the vac tree in? I just checked today if it might fit, but it looked like the small vac lines of the tree doesn’t allow to turn the tree anymore!?!
 
Are you referring to these ports? If so might not have enough room to get a factory 5.0 vac tree mounted there.
The stock 5.0 intakes were so narrow it was easier to put it on them.

 
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Are you referring to these ports? If so might not have enough room to get a factory 5.0 vac tree mounted there.
The stock 5.0 intakes were so narrow it was easier to put it on them.

I am just referrering to the right port. You can make a 3/8 thread in it, like discussed in this topic. I was just wondering if the factory vac tree will work, because it looked like there is not enough space to turn anymore. Is there any aftermarket vac tree that can be used? Any idea?

in the attached picture you see that it is possible, but is it the factory tree or any other?

regards
Felix
 

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The picture is of my intake. That is a factory vac tree.

it’s tight, but does fit. You might have to bend the small tubes in a little but I was able to get it in.

it’s 3/8” NPT