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Discussion Starter · #1 ·
okcbird said that with the new GT-40 heads that I won, I would need replacement headers. I beleive I have heard this before and that it is due to spark plug angle (maybe I am wrong). Now, if I were to buy new headers (say Mac), would the combination fit correctly in the engine bay?

Thanks
Jeremy
 

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No, the MAC and JBA headers would not work, the heads take a different style header than a normal 5.0 head (and there aren't any made for a TBird), which is why I said they wouldn't work, and yes I do believe it is the spark plug.

I'm surprised that the GT40-P's were even an option in the auction, how about a set of TrickFlow Twisted Wedge Aluminums. :)
 

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Those heads will be useless for you without custom headers. I'd see if you can resell them, and buy a set of TFS Twisted Wedge heads.
 

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You won gt40X heads I believe, not gt40p. Stock, Mac, or JBA headers should fit up to them just fine. These are the heads you won in the raffle right? I do not think gt40p's were an option. Please double check which heads you have.

John
 

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Discussion Starter · #5 ·
I just looked at the raffle and it doesn't exactly say which denomination of the heads, like X or P. It just says iron heads. I assumed that they are GT-40 "P" because in the Summit Racing catalog, the Iron Heads are given that letter.
 

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They are straight GT-40 heads with no letter designation. GT-40P's won't work because of the spark plug exit angle. The one's you won are straight GT-40 iron heads.
 

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Discussion Starter · #7 ·
Alright then, I guess I'm good eh? Haha... okc kind of got me thinking real quick about those heads. Thanks guys
 

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Discussion Starter · #9 ·
A good machinist shop can do that eh? How well do the heads like a good porting?
 

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a minor clean up/enlargement of the exhaust port roof and you should be good to go. Or you can go all out and flow close to some high $$$ heads(labour to port costs alot though).
 

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Discussion Starter · #11 · (Edited)
i was thinking that as long as i'm down that far on the engine, replacing the headers too

someone (not on the forums) said porting wouldn't do so much for the iron heads as aluminum ones? is this true? thanks for the info. guys
 

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JJanney said:
someone (not on the forums) said porting wouldn't do so much for the iron heads as aluminum ones? is this true?
They are almost the same. The aluminum ones have a lip in the combustion chamber next to the spark plug that adds swirl to the air/fuel coming into the cylinder. Because of that they make a little more power to begin with. So, it stands to reason that with a similar porting job the aluminum heads will will make more power. But, that is just because they made more power to begin with. I don't personally have experience with this. I'm just going on what I've heard and read. If someone has some ported GT-40s maybe they could chime in.
 

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Discussion Starter · #13 ·
Well, maybe I'll have some soon enough. There really isn't a good shop around this town that I would trust. Maybe in Daytona but not in this one horse town. :)
 

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Discussion Starter · #14 ·
Just checked out the heads. GT-40P's. :) Now I'm on the search for P-specific headers. I found a really good web site of information on these heads. GT-40P's (they're not that bad!)

Being as this install could have unforseen difficulties, I'm going to do it over Christmas break so I have time to change anything I need.

Central Coast Mustang sells P-specific MAC headers. Those sound like a good buy, unless I could get long-tubes to fit.

Thanks again for all the responses guys. :)
 

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good luck on your quest,
use the schwartz
I had trouble finding headers that will fit stock heads, finally got a set of jbas, ouch, as of june mac was out of t bird 5.0 headers, and they weren't planning on makin any till they got 10 orders for them.JBA had some. still only 1 1/2 primaries we'll see how they work
Mike
 

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That really sucks. I was wondering about that when I saw the GT40 heads listed because supposedly you can't get new heads from Ford any more. However, it really sucks that our club is raffling off parts that don't fit our cars with a crap. I mean, there are no GT40P headers for a Tbird, unless you build them yourself. Kinda pointless if you ask me.

John
 

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Discussion Starter · #17 ·
dode said:
That really sucks. I was wondering about that when I saw the GT40 heads listed because supposedly you can't get new heads from Ford any more. However, it really sucks that our club is raffling off parts that don't fit our cars with a crap. I mean, there are no GT40P headers for a Tbird, unless you build them yourself. Kinda pointless if you ask me.
John, I am not that bothered by it. I have been reading a lot into the heads and think it can be done. Just a lot of work. Central Coast Mustang sells the P-headers and I know headers (other than JBA and Mac) have been "made" to fit on our Birds. We'll see what happens. I know a lot of the Mustang folks on the corral are always looking for P's so I dunno. Maybe I'll do as was said earlier in the thread and sell them for TFS Aluminums. I just really want a new project, being a poor college kid and all. :)

Dugweed, I found another web site that was selling Mac's, they might have a set or two left. Actually, I know of two other web sites selling them. They might have some in storage or something. ???
 

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Hey Guys and Gals,

I've been down here in Florida for a while now , and here in southern florida we have a ton of very decent porting shops, some of which the Florida Chapter has some deals with talk to me and let me know what you want and how much you want to spend and we'll get it worked out


Jim
 

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dode said:
However, it really sucks that our club is raffling off parts that don't fit our cars with a crap.
Well, if I'd been aware of the potential issues, I would never have included them. I don't have a 5.0 and neither does Dan. We went off what we thought.

[sarcasm]God forbid anybody step up and give me a list of what really will work. That might be helpful![/sarcasm]
 
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