Header Problems... GT40Ps

Mar 23, 2020
6
1
13
48
Ft. Bragg, NC.
I need some headers advice. I have a 1968 302/C-4 Coupe with factory P/S, A/C, and P/D/B. I just bought a GT40P 5.0 (2000), and a 4R70W (2001) to put into it. I'm gathering parts right now for the install, and I'm having problems finding headers that will give the spark plug clearance that is needed. Does anyone know where I should be looking. I just got off the phone with BBK and the rep said that they don't have them. I try calling Mac Performance… no answer. Also if anyone has a set that they might want to sell, I might be interested.
 
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cwjr66

New Member
Mar 23, 2020
9
1
1
54
huntsville
Not one to sell but to help your research. I tried this with the mac headers p/n TF6466 with p heads. Read many people said these would work.

I can say, at least my pair would not clear 3 plugs enough to even keep the wire boots off the pipes. Forget even trying to put a protector in them. That was trying the autolites and accel shorties. 2 could not even get a socket on them. Test fitted on engine stand not even in car which is a 66 stang,

To add to this, these headers would not even clear the back of the 289 block without the c4 bolted on. Too narrow at the collector

My solution was reproduction Hipo 289 manifold. These do fit. 1 plug is close but I ceramic coated them and got the highest heat boot protectors I could find. hoping this works car is still at body shop.

If these dont work going with aluminum heads. Good luck CW
 
Mar 23, 2020
6
1
13
48
Ft. Bragg, NC.
Not one to sell but to help your research. I tried this with the mac headers p/n TF6466 with p heads. Read many people said these would work.

I can say, at least my pair would not clear 3 plugs enough to even keep the wire boots off the pipes. Forget even trying to put a protector in them. That was trying the autolites and accel shorties. 2 could not even get a socket on them. Test fitted on engine stand not even in car which is a 66 stang,

To add to this, these headers would not even clear the back of the 289 block without the c4 bolted on. Too narrow at the collector

My solution was reproduction Hipo 289 manifold. These do fit. 1 plug is close but I ceramic coated them and got the highest heat boot protectors I could find. hoping this works car is still at body shop.

If these dont work going with aluminum heads. Good luck CW
No.. I really appreciate it. I just got finished looking at some JBA's. They say they are P headers. So, I might give them a shot. Pricey though. Here are the part numbers if you are interested.
1650S-2JS
1650SJS
1650SJT
1650S
Thanks again for the knowledge.
 

cwjr66

New Member
Mar 23, 2020
9
1
1
54
huntsville
your welcome, Cool, might keep those in mind. Again hope they work, they were a bit high in price to experiment again. But I will say this more people said yes to these than the macs. I cheaped out, There was one other lesser known company that did make headers guarantee to fit but can't remember who and the computer dumped. used to be on ebay also so I'll check and be back
 

cwjr66

New Member
Mar 23, 2020
9
1
1
54
huntsville
To be honest, I'm not sure. I think the collector angle may not be quite right. I never really looked into that, just tried to stay in the correct years. On a side note if running a manual you will have to take in account the z bracket that the auto don't have.
 
Mar 23, 2020
6
1
13
48
Ft. Bragg, NC.
Can you run foxbody headers?
No, the fox body heads are different than the GT40P heads. The exhaust ports are positioned slightly higher up on the head, and the spark plugs are angled differently. The F/B headers don't have the spacing for the spark plug angle, and will burn the plug boots off. The P is a good head, just a pain in the butt when it comes to headers.
 
Mar 23, 2020
6
1
13
48
Ft. Bragg, NC.
Oh!!! Something of note. Holley is making a new EFI controller called the Terminator X, and the Terminator X Max. They both come with an EFI harness, but the X Max is also a 4R70W transmission controller. There is a model that is specifically for the 5.0. I'm going to use one on my swap. New EFI harness, EFI and transmission controller all in one....I'm in! They are also making EFI fuel tank modules that have the HP fuel pump on it that you put into your stock tank, and your done. No return line, and you don't have to buy an EFI fuel tank for $550. I still doing my research on all of this stuff, soooo... bare with me.
 
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beyondEOD

Member
Nov 23, 2019
37
3
8
Indiana
No, the fox body heads are different than the GT40P heads. The exhaust ports are positioned slightly higher up on the head, and the spark plugs are angled differently. The F/B headers don't have the spacing for the spark plug angle, and will burn the plug boots off. The P is a good head, just a pain in the butt when it comes to headers.
I have BBK FB headers on my gt40p heads. It works with 90 degree boots, a header plug socket and an offset wrench. For number 7 you can use a ceramic 90 boot.