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Discussion Starter · #1 ·
Does anyone know if I can use regular longtube headers in a foxbody mustang with GT40p heads? Ive people say that they can be used and they cant be used. Any help would be appreciated
Mike
 

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I run BBK Longtubes with my GT40Ps with no problems. You have to get some 90* boots for the plug wires though. Also its a BITCH to change the #5,6,7 spark plugs. You have to grind down a spark plug socket and use a wrench to turn it.
 

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Discussion Starter · #4 ·
I run BBK Longtubes with my GT40Ps with no problems. You have to get some 90* boots for the plug wires though. Also its a BITCH to change the #5,6,7 spark plugs. You have to grind down a spark plug socket and use a wrench to turn it.
thanks ,thats what I was looking for. What size primaries do you have btw? I like the bbk's but i want to get a set of headers with a 3 bolt flange.
 

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I used both bbk unequal shorties, stock shorties and ended up with flowtech longtubes in the end. All cleared well. Shorties I had to use a special plug socket. And longtubes I never changed the plugs after I got them on. Changed plugs at the same time I put the headers on. Now I upgraded to edelbrock performer rpm heads so I wont have to deal with this anymore. I also used 90* plug boots on all plugs and never even came close to the primaries.

On these heads I definatley recommend longtubes. I picked up .5 sec and 5mph changing to longtubes. That being the only change.

Combo was 308,gt40p heads, tfs1,torker 2 intake with 750dp and 5 speed.
 

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I used a set of 1 5/8" Mac lt's for a 5sp with my old gt40p head combo. Fit pretty good...had to use a couple 90 deg plug boots on a few wires.
 

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I Thought I'd do some more grave digging with these threads and ask another question. I've read through what seems to be way too many which headers fit what threads. During the past hour, i have seen nothing about mac 1 3/4 long tubes fitting. People hate on them because of the flanges but i had mine off three times before i sold them and nothing was tweaked. Another question is do i really need 3" exhaust on a P headed 306? The car is for road course so it's all mid range on up. My engine is in my sig for reference.
 

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1 3/4" headers are too big for that small of a head and you probably will not need 3" exhaust behind an engine with P heads. Once you get to 400 hp then you should consider stepping up to 3" exhaust.
 

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i run bbk equal lengths sorties and you have to dent cylinder 4 and have to use a 90 boot on cylinder 2,3,4,6,7
 

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FYI I used bbk #1515 unequal shortys worked fine except for what was mentioned in the previous post used 90 boots and i bitch for plug changing
I just ordered a set of the #1515 headers and was wanting to get plug wires ahead of time. what plugs should I ask for at the parts store to get the proper length and 90* boots and proper cap end attachments??

I kinda want my plugs to all look the same (well except for at the header itself lol) is why I ask.
 

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Hi-po manifolds

When using GT40-p heads in an early Ford with a steering box port match a set of reproduction 65 Mustang HI-PO cast iron manifolds.

I have a set of those from my 1964 Fairlane before I put a set of Super comps on it... I looked at using them on my turbocharged P-headed combo, turned around to face forwards. Did not look like it was going to work well with spark plugs and boots... what are you using? Any pics of it outside the engine bay, on a stand or anything?
 

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I just ordered a set of the #1515 headers and was wanting to get plug wires ahead of time. what plugs should I ask for at the parts store to get the proper length and 90* boots and proper cap end attachments??

I kinda want my plugs to all look the same (well except for at the header itself lol) is why I ask.
What plug wires did you end up getting?
 
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