Engine Gt 40 Head Question

gtimms

Member

Jul 21, 2012

17

2

13

South Jersey

Aug 13, 2012

#1

• Aug 13, 2012

• #1

I'm kicking around doing GT 40 heads while I'm rebuilding allot of this car. I know there are about 1 million GT 40 Head Threads, but this had me curious. I spoke to a guy today who works at a "mustang" shop we talked about doing the heads. He suggested that I switch the car to MAS since it was an 88 so that the car could deal better with the increased air/fuel issues. The only thing I've read on this is dont do the GT 40 P head and headers and replace the valve springs. ????????

 

RangerJoe

I leave the horn on while driving

15 Year Member

Apr 26, 2010

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Georgia

Aug 13, 2012

#2

• Aug 13, 2012

• #2

There is nothing wrong with using the GT40P heads. The do require special headers due to the different spark plug anlge. The P heads actually flow a touch more, not significant, and have a smaller combustion chamber, which will help to bump power a little.

If you are going to do the heads, you might as well do a cam and intake as well. You can get a GT40 Cobra intake, or use the one from a V8 Explorer. They are essentially the same, but the Explorer will cost less. There are 1000s of threads on this topic across the internet. You can literally read about them all day. And yes, you will want to replace the valve springs.

Good luck with it.

Joe

 

gtimms

Member

Jul 21, 2012

17

2

13

South Jersey

Aug 13, 2012

#3

• Aug 13, 2012

• #3

Thank you for the good info!
I still need to know about the MAS? It just seems odd to me? Not sure If hes trying to take me or thats a real concern.

 

RangerJoe

I leave the horn on while driving

15 Year Member

Apr 26, 2010

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Aug 13, 2012

#4

• Aug 13, 2012

• #4

There are a few guys who make the speed density work. But, for most cases, swapping to mass air is a must when you start making mods. The mass air can adapt to changes much better than the speed density.

Joe

 

1989DropTop

Active Member

Feb 19, 2011

269

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29

Eatonville Washington

Aug 14, 2012

#5

• Aug 14, 2012

• #5

There is nothing wrong with P heads Do a little maching work on the exhaust ports and wow!!! The spark plaugs fit I have BBK Shoties onmine with no issues!!

 

pissedoff92

Member

Aug 14, 2011

288

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18

western new york

Aug 15, 2012

#6

• Aug 15, 2012

• #6

I too have heard that the speed density doesnt adapt as well to mods like a lopey cam. At some point I think most of they guys on here convert to mass air to work better with mods. You can do it pretty cheap as well

 

rd

Founding Member

Jan 12, 2000

3,316

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109

Ocean Springs MS

Aug 15, 2012

#7

• Aug 15, 2012

• #7

Have two sets of plain iron GT40s, love them. One set from SVO, one set from a 94 Lightning. Love them, they really woke up the car.

 

Mike86Stang

Advanced Member

Apr 11, 2000

10,296

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77

Red Lion, PA

Aug 15, 2012

#8

• Aug 15, 2012

• #8

Generally you don't need to step up to Mass Air until you start playing with the cam. I had Edelbrock RPMs and a Holley Systemax II intake on my last car with a stock cam and ran great, swapped to Mass Air Flow after I cammed it.