What headers - GT40 heads?
- Thread starter phutch11
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CraigMBA
New Member
I have GT40x heads. JBA, Hedman, and those crappy tri-y pieces all clear with no problems.
Do you have GT40P heads off an explorer by any chance?
Do you have GT40P heads off an explorer by any chance?
No just normal GT40 irons.
The cheapo headers fit the E7 heads I originally had. But I had to heavily clearance the tubes of cylinders 2, 5, 6 to get them to bolt up. And I'm still burning plug boots on 5 and 6.
I hate to plunk down the cash not knowing if they'll fit.
Which headers do you have on the car currently?
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The cheapo headers fit the E7 heads I originally had. But I had to heavily clearance the tubes of cylinders 2, 5, 6 to get them to bolt up. And I'm still burning plug boots on 5 and 6.
I hate to plunk down the cash not knowing if they'll fit.
Which headers do you have on the car currently?
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Reviving my own dead post. Last time around I cheaped out and put some new spark plug wires on the car and they lasted about 9 months.
I'm not going the cheap route again.
Looking for a set of headers for gt-40 heads on a 64.5-66 mustang. Anyone else besides CraigMBA?
Which headers exactly are you running?
Thanks guys...
I'm not going the cheap route again.
Looking for a set of headers for gt-40 heads on a 64.5-66 mustang. Anyone else besides CraigMBA?
Which headers exactly are you running?
Thanks guys...
Decurion
Member
gt40 heads have the same spark plug angle as all the other heads. Only one with a different angle is the P heads. How many bars on the front of the head? 4?
3, they are 40s not 40p's. And no they don't have the same angle. If they did the tri-Ys that fit perfect on my e7's would fit perfect on these too.
They don't, as mentioned above they required a lot of work to get them to fit at all.
Do you have GT40s on your car, if so, what headers do you run?
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They don't, as mentioned above they required a lot of work to get them to fit at all.
Do you have GT40s on your car, if so, what headers do you run?
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65ShelbyClone
Founding Member
GT-40s are a direct swap for E7s. My Edelbrock 60379s are also a direct swap for E7s and I have regular smallblock headers for '65-73 289/302 Mustangs and 45° wire boots with no clearance problems.
Are you absolutely sure you don't have GT-40Ps?
Are you absolutely sure you don't have GT-40Ps?
100% sure. They have the three vertical bars and say GT40 in the valley.
I can assure you that they are not a direct swap. Have you had a set in your early Mustang that you've swapped directly? The reason I ask is not to be a a**, but b/c I'd like to talk to someone that has done what I'm doing.
The tri-ys fit on the e7's like a glove, with 45 degree boots. With the GT40s I had to almost completly crush the primary from #5 and lightly dimple #2 and #6 to get shorty plugs with 90 degree boots on.
Personally I think that the "direct swap" myth has trickled down from the fox 5.0 world - likely that all widely avialable headers for a foxes with e7s also fit GT40's but not Ps. Thus everyone assumes the drop right in for all body styles.
What shocks me is that I've had this same thread posted on this and other sites for days and despite the number of threads you see comparing GT40 heads to everything under the sun - there's yet to be anyone with iron GT40s on their early Mustang to respond. I thought this had to be the most common setup in the world. Go figure.
I can assure you that they are not a direct swap. Have you had a set in your early Mustang that you've swapped directly? The reason I ask is not to be a a**, but b/c I'd like to talk to someone that has done what I'm doing.
The tri-ys fit on the e7's like a glove, with 45 degree boots. With the GT40s I had to almost completly crush the primary from #5 and lightly dimple #2 and #6 to get shorty plugs with 90 degree boots on.
Personally I think that the "direct swap" myth has trickled down from the fox 5.0 world - likely that all widely avialable headers for a foxes with e7s also fit GT40's but not Ps. Thus everyone assumes the drop right in for all body styles.
What shocks me is that I've had this same thread posted on this and other sites for days and despite the number of threads you see comparing GT40 heads to everything under the sun - there's yet to be anyone with iron GT40s on their early Mustang to respond. I thought this had to be the most common setup in the world. Go figure.
I run GT-40s in my '88 fox and use the Summit coated shortie headers. Fit is great and finish has stayed perfect for 2 years now. Absolutely no problems with plugwires.
I am in the process of swapping a GT-40 topend into my '68 and plan on using the same Summit headers.
I know you are looking for long tubes, but the shorties worked great for me
I am in the process of swapping a GT-40 topend into my '68 and plan on using the same Summit headers.
I know you are looking for long tubes, but the shorties worked great for me
Decurion
Member
I have gt40 heads on my 65 Comet with Hedman 88400 headers, and no problems.
I know you say youre 100% sure you dont have P heads, but maybe you should take a pic of the front of the head to prove it to the rest of us. I had a set of unknown Hooker headers on some unknown 302 heads in my Comet and they fit great. Switched to Windsor Jr heads and they fit terrible (relocated plugs), then put the headers on a 65 Falcon with gt40 iron heads and they fit great. Heres pics of the Hedmans on gt40 non-P irons.
Heres the P heads
I know you say youre 100% sure you dont have P heads, but maybe you should take a pic of the front of the head to prove it to the rest of us. I had a set of unknown Hooker headers on some unknown 302 heads in my Comet and they fit great. Switched to Windsor Jr heads and they fit terrible (relocated plugs), then put the headers on a 65 Falcon with gt40 iron heads and they fit great. Heres pics of the Hedmans on gt40 non-P irons.
Heres the P heads
Thanks for the great reply - now we are getting somewhere. Ill check and see if those hedmans will work on my car.
They are GT40s with the 3 bars and all.
My camera cord is missing and I'm headed to Vegas for the weekend so it may be a bit befor I can get the picks up.
If you care to search, I posted a thread that detailed my port job on the heads on this site that has tons of pics of my heads.
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They are GT40s with the 3 bars and all.
My camera cord is missing and I'm headed to Vegas for the weekend so it may be a bit befor I can get the picks up.
If you care to search, I posted a thread that detailed my port job on the heads on this site that has tons of pics of my heads.
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65ShelbyClone
Founding Member
I found those pictures you posted in the Word docs. Looking at the chambers and the plug bosses, your heads are definitely GT40Ps or at least have the same plug orientation as GTPs.
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FullSizeBronco.com - 78 - 96 Ford Bronco offroad club, forums, tech, installs
I might be inclinded to agree with you if it wasn't for the stuff not captured in that thread - i.e. the three bars on the front of the heads, the "GT" casting, and the wierd off-sized plugs the head takes.
They are GT-40s.
http://www.stangnet.com/mustang-forums/774610-how-port-iron-gt40s.html
I will say that in the pictures that Decurion posted, those Hedman's on the #5 cylinder go down and then back. My tri-ys barely dip at all before heading straight back at the #5.
They are GT-40s.
http://www.stangnet.com/mustang-forums/774610-how-port-iron-gt40s.html
I will say that in the pictures that Decurion posted, those Hedman's on the #5 cylinder go down and then back. My tri-ys barely dip at all before heading straight back at the #5.
65ShelbyClone
Founding Member
I guess you could have some weird early casting. In my searching I found mention of a GT40 head that had E7TE casting numbers and the raised "GT" letters by a spark plug hole.
Either way, the combustion chamber photos you posted look exactly like the GTP.
Either way, the combustion chamber photos you posted look exactly like the GTP.
Decurion
Member
In your article on how to port heads you mentioned you had to buy new valves. What size were the exhausts? P heads have smaller valves than non-P heads. Im with 65Shelbyclone on this one. Youve got P heads. Maybe some oddball ones marked as GTs, but the plug angle and chamber volume both seem to say theyre P heads. Non-P heads have ~63cc chambers, and P heads have ~59cc chambers, which after milling would bring them to the 57cc you claim. Youd have to mill the non-Ps almost .050 to get them that small.
I have the big exhaust valves, not the small ones.
Who knows maybe ive got some odd heads? When I can post some pics you guys will be able to see what I'm working with.
I do appreciate all the help in identifing the heads, but back to the original question....
Anyone with first hand experience on an early mustang? What headers do you use?
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Who knows maybe ive got some odd heads? When I can post some pics you guys will be able to see what I'm working with.
I do appreciate all the help in identifing the heads, but back to the original question....
Anyone with first hand experience on an early mustang? What headers do you use?
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CraigMBA
New Member
Okay, so I've finally gotten the camera cord and the pictures loaded to my computer. I haven't ever posted pictures on here, so the next few posts may get ugly.
The first shows the 3 bars and a little bit of the issue I have on #5.
Second shows clearly the "GT" casting.
The third shows the issues on #5 and #6.
I'll be damned if it doesn't look like I have the GT-40P plug angle. Look at the second picture I posted and then compare it to the pictures posted above. Look at how on the GT-40 heads posted earlier, the plug covers the "GT" casting, but on my heads, the plug doesn't seem to cover the casting.
WTF heads do I have? Has anyone ever seen this before?
The first shows the 3 bars and a little bit of the issue I have on #5.
Second shows clearly the "GT" casting.
The third shows the issues on #5 and #6.
I'll be damned if it doesn't look like I have the GT-40P plug angle. Look at the second picture I posted and then compare it to the pictures posted above. Look at how on the GT-40 heads posted earlier, the plug covers the "GT" casting, but on my heads, the plug doesn't seem to cover the casting.
WTF heads do I have? Has anyone ever seen this before?
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