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5.4L dohc in 86 GT. Which headers??

n2ostang

Member
hey guys i have a 86 GT and a navi motor and im trying to figure out what headers will work or what mods i have to do to a set to make work? long tubes or shorty? any help would be greatly appreciated. thank you
 

n2ostang

Member
hey guys i have a 86 GT and a navi motor and im trying to figure out what headers will work or what mods i have to do to a set to make work? long tubes or shorty? any help would be greatly appreciated. thank you
 

ModFoxMustangs

Well-Known Member
Staff member
Shorty will fit with no problems it the long tubes.. That you have to worry about.. We used JBA mid length headers they look like Long tubes.. I can contact them and see if they make a special conversion set... I will have them log on today to answer questions.
 

Bill

Well-Known Member
Staff member
Donator
Mod motor dimensions.JPG
Please forgive me for my blatant act of plagiarism. I stole this from the Sullivan Performance web site (many moons ago) for personal use.
This is why longtube headers are an issue on the 5.4 conversion. By the time you're down to the ports, the difference is about 1.25 inches, but 5/8" on each side is a lot when it comes to longtube clearances. I have seen several make it work with a rosebud and a pry bar. You have to decide how bad you want LTs.
 

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n2ostang

Member
I dont really care if i use shortys or lontubes or even mid-lengths. i just want something that works lol. I did find bassani mid-lengths and x-pipe for 500
 

Bill

Well-Known Member
Staff member
Donator
Are you going to have to pass any sort of emissions test, visual inspection or CARB verification?
 

Bill

Well-Known Member
Staff member
Donator
The short of it. The 5.4 SOHC shares the same exhaust port and bolt configuration as the 4.6 SOHC. The same is true for the 5.4/4.6 DOHC. A good quality set of short tube headers will make your swap work fine (DOHC/Cobra, SOHC/GT). Stick with something that stays fairly tight to the motor. The nice curly equal length stuff will be too tight. The 5.4 takes just over 1/2" per side more than the 4.6 (9/16") and the ports are slightly higher. You'll hear many of the folks here be partial to JBA, including me. Doug's Headers also has a really good option and gives you the choice of 2 1/2" collector or 3" collector, both with 1 5/8" primaries. Doug's is also a bit more generic in fit. I know they (JBA) are more expensive, but it is very true that you get what you pay for in headers. The bottom line on them is that if you don't get a good solid warranty with them, there is a reason for that.
 

Bill

Well-Known Member
Staff member
Donator
Is it a SOHC or DOHC? The SOHC headers from JBA are the same on the 96-98. They are different from 96 to 97-98 on the Cobra headers. Open a private conversation with ModFoxMustangs (your site admin). He is a current dealer and can give you a quote. Justin Williams is also on here. He is THE MAN for tech questions about JBA/DOUG's etc. He's forgotten more about headers than I ever knew.
 

Bill

Well-Known Member
Staff member
Donator
That will be an awesome build. I would probably go with the 1625S-5JT or the 1625S-6JT.
 

Bill

Well-Known Member
Staff member
Donator
Are you pulling it out of a donor car? The reason I ask (and one of the tricks I've learned over the years is relative to all the little electronic gaggets that have to be in the right place to make the wiring fit right), if you are, I have learned that when you are disassembling the engine compartment, if it is attached to the engine and you can leave it attached, do so. All the little wiring and devices that make it all work can usually be taken loose from the apron or fire wall and piled up or taped/wired to the motor for relocation. What this does for you is allows you to reinstall each device without having wire/hose length problems and without having to figure out where it all hooks up. You'll see me (and probably others) doing this here. Yes, it looks like a giant heap going into the hole, but it takes hours/days off of an installaiton for someone who doesn't do this kind of work alot. I wish someone had told me this on my first build (or my second), but that wasn't the case. I'm really looking forward to seeing your 5.4 go together. That's a swap I'm interested in doing as well at some point as well.
 

Bill

Well-Known Member
Staff member
Donator
On a side note and good news for the JBAs, they are CARB exempt and have the E.O. tag welded on them. If you ever move or your emissions laws ever change, you can retrofit functional emissions onto your ride, change your tune and go let'm sniff you.
 

Bill

Well-Known Member
Staff member
Donator
I'm looking forward to seeing it come together. I have started acquiring the parts to do the MSD set up as well, but so far all I've picked up is the four ignition adapter modules. I will get the rest as funding permits.
 
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