Headers 4.6 and 5.4

[MickeyD]

Well, I have an exhaust leak at the header on my passenger side. I think this is stemming from when i spit a spark plug out of the head on that side a year ago (i don't drive the car much) and want to get this fixed this winter. Now i plan on going with a 5.4 engine swap in the next couple of years and i know what a pain it is to do header work on these cars.

So, I'm thinking if i were to be going in to fix an exhaust leak might as well upgrade the headers since I'd be removing them anyway to take care of the leak. With my future plans though is there a header that would work for both a 4.6 DOHC and the 5.4 DOHC? I have a feeling they won't work for both but figured I would see.

 

[01yellercobra]

If you keep your current heads they should work. You'll have to modify the mid pipe because the collectors will be a little further apart from the wider block. My understanding is if you go with a 5.4 head (GT, Navigator) then you'll need different headers because the spacing between the ports is a little more then the 4.6 heads.

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[na svt]

The 5.4 and 4.6 exhaust port spacing is exactly the same. The GT heads have a different bolt pattern but the header flanges can be modded to fit.

With that, the 4.6 headers will not fit a 5.4 when installed in a mustang.

 

[MickeyD]

Thanks for the input, I figured it wouldn't be a direct swap over and that I would end up having to get different headers for a 5.4 swap but never hurts to find out for sure. Guess I'll just have to do some work to get things running right while I set things aside for my engine build.

 

[Ironhand]

The 5.4 and 4.6 exhaust port spacing is exactly the same. The GT heads have a different bolt pattern but the header flanges can be modded to fit.

With that, the 4.6 headers will not fit a 5.4 when installed in a mustang.

This is wrong.

I got off the shelf ARH 1 3/4 x 3 03-04 Cobra longtubes to fit on a Navi headed iron 5.4 without any header modification.

 

[na svt]

I got off the shelf ARH 1 3/4 x 3 03-04 Cobra longtubes to fit on a Navi headed iron 5.4 without any header modification.

Those are the exception then. it's been tried with others and they had to be modded.

 

[Ironhand]

Those are the exception then. it's been tried with others and they had to be modded.

Well actually since I reread that I realize I had a brain fart.

They fit with a different steering shaft.

 

[MickeyD]

Well actually since I reread that I realize I had a brain fart.

They fit with a different steering shaft.

Did you have to switch the steering shaft for the 5.4 anyways? If so this may be a good option for me.

 

[01yellercobra]

Is there a difference between the long tubes and shorties fitting? I know a local guy that swapped a 5.4 into his GT. But I think he used shorty headers.

 

[Ironhand]

Did you have to switch the steering shaft for the 5.4 anyways? If so this may be a good option for me.

The cast iron pieces take up alot less room then Longtubes.

I do a drop k member that allows larger blowers to clear my stock 03-04 Cobra hood. That put the headers in the way. So I made a steering shaft that is thinner then the stock piece and it clears the headers.