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1988 Ford Mustang GT with a 1989 GT 5.0
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Discussion Starter · #1 ·
If i bought a set of Gt40 head could i run rockers for a normal foxbody 5.0 head? Also is there any way to combat the GT40p heads burning the plug wires? I have a set of unknow long tubes and would like to use them.
 

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Yes, if the rockers don’t interfere with the replacement springs you install.

and yes, there are P specific headers that don’t have any issues burning wires.
You have a 50/50 shot at your unknown longtubes working
 

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Discussion Starter · #3 ·
Yes, if the rockers don’t interfere with the replacement springs you install.

and yes, there are P specific headers that don’t have any issues burning wires.
You have a 50/50 shot at your unknown longtubes working
Is there any reason to choose the p heads? Other than compression.
 

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Is there any reason to choose the p heads? Other than compression.
price & availability.
About $200 & a spring kit and you’re set.

Compression isn’t a factor.

but then you also have to factor in a P header, so there really isn’t any savings
 

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P specific headers are hard to find for a mustang and when you do find them they will be expensive. The power gains aren't from compression, it's from the chamber and runner design along with the straight angle plug if i remember correctly.
 
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I run non P specific longtube headers, with no burned wires. You just need two wires with 90 degree boots and maybe a heat sleeve if it is real close and you are done. That probably will work on 99% of the headers.
 
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Discussion Starter · #9 ·

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Discussion Starter · #10 ·

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I have shorties that are not ‘P’ specific headers and they work fine. #7 plug wire is close but no issues with a 90 degree boot and heat sleeve for 3 years now. If you can get them for a good price run them. Just make sure you’re not spending close to an entry level set of aluminum’s when it’s all done.
 

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Discussion Starter · #14 ·
I have shorties that are not ‘P’ specific headers and they work fine. #7 plug wire is close but no issues with a 90 degree boot and heat sleeve for 3 years now. If you can get them for a good price run them. Just make sure you’re not spending close to an entry level set of aluminum’s when it’s all done.
Yeah what plugs wire do you run?
 

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I have shorties that are not ‘P’ specific headers and they work fine. #7 plug wire is close but no issues with a 90 degree boot and heat sleeve for 3 years now. If you can get them for a good price run them. Just make sure you’re not spending close to an entry level set of aluminum’s when it’s all done.
You are right. I did a P head swap on my 95 GT vert and #7 and I think #4 was a PITA plug boot wise. I had to slightly ding the header tube on my Mac shorties, I also used 90 degree wire set from a chevy but still had to use 1 shorty Accel spark plug on #7. I was wanting to buy all 8 plugs but Jeezus, they are almost $20 each.All in all, the swap was worth it to me. Combined with the cam and Alex's .540 spring kit it has a decent power increase from the E-7s.
 

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Discussion Starter · #19 ·
You are right. I did a P head swap on my 95 GT vert and #7 and I think #4 was a PITA plug boot wise. I had to slightly ding the header tube on my Mac shorties, I also used 90 degree wire set from a chevy but still had to use 1 shorty Accel spark plug on #7. I was wanting to buy all 8 plugs but Jeezus, they are almost $20 each.All in all, the swap was worth it to me. Combined with the cam and Alex's .540 spring kit it has a decent power increase from the E-7s.
Oh cool I’ll just ding my long tubes I if I have to
 

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Oh cool I’ll just ding my long tubes I if I have to
I would have rather had correct fit headers believe me. Was a pita but P specific shorties were noexistent and the $ of long tubes was out of reach for the budget I had, but I have no leaks and the head swap has worked out and runs nice the last 5 years.
 
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