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Discussion Starter #1
Has anyone bought the Ford GT-40 Cast Iron heads for their small block Fords?
The Ford Racing catalog (drool) :p: has them complete w valve train (less rockers and screw-in studs) for $270. I would be hard pressed to be able to rebuild my old heads for less.
Just wondering about the performance improvements and what anyone thinks.
 

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Garey,
For that price, you are probably talking about the GT40P heads.
look in the part number, there should be a P somewhere. The GT40P heads are completely different than the GT40 heads.

The P was used on the 5.0 explorer and has relocated spark plug and a more efficient design. They require specific headers.

The GT40 was used on the 93-95 cobra, and will bolt up to the standard header.

Check out GEF for good prices and the other one for GT40P info

GEF

http://www.geocities.com/motorcitymustang/gt40p.html

Hopefully I will be going to your area soon to pick up the rear. (as soon as Steve yanks it out)
 

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Be careful on the "P" head. Your exhaust probably won't fit. Ford is selling the ho-hum GT Mustang head from the late model era. It is *not* the cast iron GT40 head. It's the RPO head (read: boring).
The "P" head gets a lot of good marks but doesn't compare to the GT40 aluminum head. There are lots of other good heads out there but for $185.00 each (GT Mustang head from GEF p/n: M6049M50) you can't go wrong for all new parts...
 

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dfw-
that part number for $185 is the "ho-hum" GT/LX mustang head offered on stock 87-93 mustangs with the 5.0 .

Your headers for stock heads dont really fit the P heads. If you bash a few pipes with a BFH they will, but you will burn the hell out of your plug wires. I would get the "P" specific headers from
central coast mustang. They make longtubes for around 300$
 

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Discussion Starter #5
The Ford Racing Catalog says fits all small block fords and uses either cast iron intake or aluminum.
Does the problem come into play with Headers? what if you used Mustang(65-66) Hi-po exhaust manifolds?
 

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Discussion Starter #6
Well, I am searching for answers to see if anyone has installed these in a early Mustang or Cougar. I have also talked to GEF and Central Coast Mustang.
GEF says the only headers that will work are the GT40P shortys. He also said they would fit the 67 Cougar.
CCM says they will not, and sell long tube headers for 65-70 Mustangs(Cougars).
Well why wouldn't short tube headers work?
Crud, nothing like buying something that won't bolt on directly.
 

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I happen to have a brand new set of the GT-40P heads in my basement, still in the boxes.... They have the 1.94"/1.54" stainless valves installed, as well as the stud bosses milled/tapped to accept screw in studs and the necessary push rod guides. I did a trial fit on my motor since I already had my old heads off... Just set em' on there without a gasket... Looked to me like the headers I have would work with the revised plug layout... But I havn't run them and didn't go all the way so I don't know for sure. I ended up porting my 289 heads and running 1.94"/1.60" valves... ended up with over $600 in those Bas#@*%. But I'm not bitter about it... I'd sell the GT-40 P's I've got, with the valves, for $450 if you decide to go this route. These were professionally prepared at tri state cylinder head and have 11 mos. of warranty left... I'd suppose its transferable but I can't know for sure.

Ron.
 

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Discussion Starter #8
Did you buy them bare? The Ford Racing catalog shows them complete with all valve train less rockers and studs(screw-in). I have found them @ the GEF link above for $480 for the set.
You don't have rocker arms for them do you?
I am guessing you have a 67 or early 68 because you mentioned you had used your 289 heads.
What headers do you have that looked like they would clear and do you think you could get the shorty headers to work?
Thanks
 

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http://www.geocities.com/motorcitymustang/plug01sm.jpg


Above you can see the change in plug location from the GT-40 (right) to the GT-40P. (left)
(the site wont let me post image, I have to post link)

look at the plug location. the P head has the plug closer to the exhaust port. If you could imagine that would bring the standard headers reeeeeal close to some of the plugs because of the bends. I have heard of people bashing the standard header pipes a bit to gain clearance, but you will burn the plug wires up.

I am not sure if the P specific headers would fit our application. You know you want the longtubes anyway....
 

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I just re-read my posting. I knew that (what you said) but maybe my email wasn't clear. I was just pointing out that Ford was *also* selling the GT (ho-hum) head for $185 which wouldn't give him fitment problems like the more expensive (albeit marginally better "P" that was mentioned). Thanks for the clarification.

CrazyCat said:
dfw-
that part number for $185 is the "ho-hum" GT/LX mustang head offered on stock 87-93 mustangs with the 5.0 .

Your headers for stock heads dont really fit the P heads. If you bash a few pipes with a BFH they will, but you will burn the hell out of your plug wires. I would get the "P" specific headers from
central coast mustang. They make longtubes for around 300$
 

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These heads are different from the ones in the catalog for these reasons:

"Catalog" heads come with 1.84"/1.48" valves, these heads are machined for, and fitted with 1.94"/1.54" valves, markedly improving flow without port work. (which could be done to improve flow even more)

"Catalog" heads must be machined in the area of the stud bosses; they are set up for the late model bolt on style rocker assemblies. The bosses must be milled 0.300" or so to change over to the screw in style studs and the guideplates necessary in the older model stud mount adjustable rockers.

Catalog heads come with anemic valve springs, you would want something more for even a mild performance cam. These heads do not have springs; springs should be bought with the cam that you select, as specified by the cam manufacturer. These heads are fitted with the positive style valve seals.(the kind that go over the top of the valve guide)

By the way, my car is a highly modified 302, running 289 heads with big valves. (289 heads have smaller combustion chambers, improving compression without going to pop up pistons; flat top pistons WILL interfere with my cam 0.560"/ 0.560", and the bigger valves, so flycutting of the valve reliefs is required) My motor makes around 400 HP, but isn't really user friendly on the street. Rough idle, hot, etc... I havn't made any recent passes at the strip, but ran 14.40's on a poorly tuned motor and a hot day, before spending another $1000 on my cylinder heads. I hope to be in the low 13's or high 12's.

As far as what kind of headers I have, I THINK they are hooker long tubes, but since they came with the car when I bought it, I cant be at all sure. I have no knowledge or experience with the "shortie" headers to be able to say whether or not they would work. Sorry for the lack of assistance with the headers.

Keep in mind that the machine work required to use the GT40P's with the older model cars is a bare minimum of the stud boss milling. (which is already done on these)

Ron.
 
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