Iron GT-40 Head question

95CobraMike

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Apr 12, 2004

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Lima OH

Dec 18, 2005

#1

• Dec 18, 2005

• #1

What size combustion chambers are on the iron gt40 heads?

Thank you

 

18mustangs

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Jun 8, 2005

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Virginia Beach, VA

Dec 18, 2005

#2

• Dec 18, 2005

• #2

95CobraMike said:

What size combustion chambers are on the iron gt40 heads?

Thank you

Click to expand...

That depends where the GT40 heads are from. Cobra GT40 heads have 61cc chambers (I can verify this fact later but don't have my resources at hand) and the Explorer GT40 heads have larger combustion chambers.
Tim

 

95CobraMike

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Lima OH

Dec 19, 2005

#3

• Dec 19, 2005

• #3

Yes i am intrested in cobra GT-40's

 

95CobraMike

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Lima OH

Dec 20, 2005

#4

• Dec 20, 2005

• #4

^^^

 

legalize420

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May 21, 2005

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Dec 20, 2005

#5

• Dec 20, 2005

• #5

http://www.themustang-net.com/tech_articles/gt40p.shtml

65.5 according to this

 

D

db1994

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Lake Worth, FL

Dec 20, 2005

#6

• Dec 20, 2005

• #6

65.5 is off the shelf. The heads as they came on the car were a lot smaller chambers since the comp ratio of a 94-95 cobra was 9.35:1 not the 8.8:1 listed in that article.

-Jason

 

H

hrspwrjunkie

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Dec 15, 2004

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Dec 20, 2005

#7

• Dec 20, 2005

• #7

The Official Ford Mustang 5.0: Technical Reference & Performance Handbook, 1979-1993 lists the combustion chambers as between 63 and 65.5cc on the '93-'95 Cobra heads as well as the Motorsports version which varied only slightly from the production head.

Explorer heads are at approximately 60-61cc.

 

18mustangs

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Dec 20, 2005

#8

• Dec 20, 2005

• #8

legalize420gt95 said:

http://www.themustang-net.com/tech_articles/gt40p.shtml

65.5 according to this

Click to expand...

That seems like it's talking about Explorere GT40 heads as they need to be milled to give the stock mustang compressions ratio. (I'm guessing here as my Ford Technical CD is still in transit from my move) but GT40s on cobras had 61cc and E7TE had CCs ranging from 61-63 cc each (mass produced GT heads had looser tolerances that Cobra GT40 heads.)
Tim

 

95CobraMike

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Lima OH

Dec 20, 2005

#9

• Dec 20, 2005

• #9

So if i were to go with a set of heads with 64cc combustion chambers i would have around stock cobra comp. ratio?

the gt-40's on there now have been milled 2 times and i think my comp ratio is too high

 

final5-0

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Apr 6, 2003

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DFW Texas

Dec 21, 2005

#10

• Dec 21, 2005

• #10

95CobraMike said:

So if i were to go with a set of heads with 64cc combustion chambers i would have around stock cobra comp. ratio?

the gt-40's on there now have been milled 2 times and i think my comp ratio is too high

Click to expand...

Not totally sure here Mike
but
It has always been my understanding that when talking about oem iron heads

you can't mill them all that much before you start to have alignment issues.
Even if you go to that maximun point or just before you have those probs ...
the amount of gain in compression is not all that much.

I don't think you can even gain 1/2 a point

Grady

 

W

wytstang

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Mar 14, 2004

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Summerville,SC missing South Fl. weather :(

Dec 21, 2005

#11

• Dec 21, 2005

• #11

CObra GT40 heads=64/65cc Exploder GT40p heads=60cc IIRC.

 

blksn955.o

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st.louis mo 314

Dec 21, 2005

#12

• Dec 21, 2005

• #12

Mine are milled .065 and I had to get the lower intake milled to fit correct. I belive the max without milling is like .050-.055 or something like that. I had the intake milled like .025 so it would still be usable and in speck if ever sold (well could be used if someone had a very mild mill on there heads).

I though I saw a thing about the cobra heads (93-95) that the gt40 heads on them were milled from the factory a hair...this could explaine the diff. in "off the shelf" numbers and what others are putting up.

 

S

stang2841

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palm harbor florida

Dec 21, 2005

#13

• Dec 21, 2005

• #13

GT40 heads = 63-65 cc.. they vary .. atleast the ones I've seen and the different years


GT40p = 58-61 cc they also vary..

you need about 5-8 cc taken off for about half a point in compression maybe a bit more...

you can typically go .25-.30 safely without alignment issues/pushrods.