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1968 Mustang GT
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Discussion Starter #1
I’m getting ready to start the beast. I have a 68 Fastback with a 302, brawler carb, T5, factory air and manual brakes. I’m looking for the correct heater hose and fitting for the intake. Oddly holley has nothin on the size. I think it’s half inch NPT but what about the hose? Ive also read in a couple old threads that the standard 90 elbow will conflict with runner. Is that true?

Lastly, do I need to install a vacuum fitting tree for additional connections? I know the carb has 2 timed vacuum ports. One should go to the distributor.

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The manifolds are normally tapped with a 3/8" NPT. 1/2" NPT is possible. The heater hose is 5/8".
How many vacuum sources do you need?
 

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67 coupe, 69 Sportsroof, 86 hatchback
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I never liked the rubber heater hoses all over and so used a 1990's type Mustang metal heater hose set. I got mine off an actual Mustang engine but you can buy new ones. Here's the first example I Googled up. The picture shows it upside down so you're looking at the threads for the intake.

The rear vacuum port I didn't use. I don't have power brakes or an automatic transmission that needs a vacuum signal. I will eventually need a small vacuum line for my air conditioning but since it will be the only one I might just use the carburetor vacuum tap that's already there but currently capped off.
 

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Discussion Starter #5
Can I use the rear port on the runner for the feed to the heater?
 

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Discussion Starter #6
I don’t think it’s 3/8 Maybe 5/8” Or 3/4”?? Odd. This was measured at the top. I know it’s a tapered thread.

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Discussion Starter #8
Thanks but I don’t think that’s it I can drop a 5/8 tube down the hole. I think its 3/4 inch. Not sure why so big. If we weren’t in lock down I could go down to The hardware store and just pick up a few different sizes. But that’s not going To happen any time soon.
 

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Thanks but I don’t think that’s it I can drop a 5/8 tube down the hole. I think its 3/4 inch. Not sure why so big.
You do not understand NPT sizes. That's the issue. The hole for a 1/2" NPT is .72"

I would not use that reducer, it might be a pain to get out later. On my RPM AirGap Manifold I just got a 90 degree fitting from the hardware store that had a 1/2" NPT to 5/8" barb. You can see it here:
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If we weren’t in lock down I could go down to The hardware store and just pick up a few different sizes. But that’s not going To happen any time soon.
Holy Mackerel! You can't even go to the hardware store? We'd have another revolution here in Texas if we couldn't go to the hardware store, auto parts store, junk yard or Whataburger!
 

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Discussion Starter #13
Yes, vacuum tubes control the heater. I've also just realized I need the heater control valve too.

Yup, all of our hardware stores and autoparts stores are curb side pickup only right now. So I need to make sure I'm calling for the right part.
 

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I would not use that reducer, it might be a pain to get out later. On my RPM AirGap Manifold I just got a 90 degree fitting from the hardware store that had a 1/2" NPT to 5/8" barb.
I used that reducer because it's a cleaner look, barely noticeable. Can't think of a good reason to ever remove it. The standpipe on the stock 90 deg. fitting is there to keep air out of the heater hoses/core.
 

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You do not understand NPT sizes. That's the issue. The hole for a 1/2" NPT is .72"
^ ^ ^ This. The heater TUBE, itself, is 5/8 inch, but the fitting is 1/2NPT.

A couple solutions possible with intakes with tall runners. First is to use a banjo fitting. Mishimoto makes a CNC aluminum fitting with a 5/8 hose barb. You'd need a 1/2NPT to metric adapter. See photo below. Option #2 is to use a 1/2NPT threaded nipple as a standpipe (I'd thread the ID and insert a restrictor down to 3/8"ID in the bottom end... and use a swivel and hose barb to connect.

 

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Ok, about ready to go to bed............so why are you using an open fitting? I thought there was a thread not too long ago about the proper manifold fitting being a fitting with a restriction in it to cut down the flow to the heater core............see pic.......if your talking about something else.....well i;m half asleep............

sandybob
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As the owner of a Weiand Stealth, I can confirm that you CANNOT use a stock Mustang heater hose outlet because that runner will get in the way. It's really annoying. You can use one of the super-tall ones - I think for a late 60's Shelby maybe? - but then your heater hose will kind of be hanging out in midair.

My somewhat inelegant but very functional solution was to put together three pieces: a basic male-male coupler (forget what the sizes are, not helpful, sorry), an elbow, and a male-to-barb adapter. The male-male coupler helped raise the height a bit so the elbow could screw on, squeaking past the runner. Then because I couldn't find an elbow with the right barb outlet at the time, I needed that male-to-barb adapter for the other end to attach the heater hose to. IIRC I did this because at the time I was having a hard time finding what I really wanted, which was one of those post-style fittings that looks similar to the stock-style heater hose fitting, but with a removable threaded barb sticking out at a 90* angle instead of it being all one piece. At the time I needed to get back on the road so I just went with what I could find at Lowes, but I have no doubt that such a beast exists and is probably a more elegant solution.
 
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As an addendum - both of Bart's suggestions would probably work well. The banjo fitting would need a stand-off fitting of some sort though because otherwise it would run into hump at the base of the runner.

Originally I had wanted to go with his second idea (right angle threaded nipple + hose barb), which is what I was trying to describe in my above post, but I was unable to find a combo that would work at Lowes/Home Depot.
 

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As the owner of a Weiand Stealth, I can confirm that you CANNOT use a stock Mustang heater hose outlet because that runner will get in the way. It's really annoying. You can use one of the super-tall ones - I think for a late 60's Shelby maybe? - but then your heater hose will kind of be hanging out in midair.

My somewhat inelegant but very functional solution was to put together three pieces: a basic male-male coupler (forget what the sizes are, not helpful, sorry), an elbow, and a male-to-barb adapter. The male-male coupler helped raise the height a bit so the elbow could screw on, squeaking past the runner. Then because I couldn't find an elbow with the right barb outlet at the time, I needed that male-to-barb adapter for the other end to attach the heater hose to. IIRC I did this because at the time I was having a hard time finding what I really wanted, which was one of those post-style fittings that looks similar to the stock-style heater hose fitting, but with a removable threaded barb sticking out at a 90* angle instead of it being all one piece. At the time I needed to get back on the road so I just went with what I could find at Lowes, but I have no doubt that such a beast exists and is probably a more elegant solution.
Same here. I also have a Stealth. The stock heater tube won't work. The intake runner is too tall and not enough room to turn the nipple. I used a brass 1/2" NPT street L with a barbed nipple.

Tubing is measured by the outside diameter and pipes are measured by the inside diameter
 
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