GT40 heads

[94snake]

Im about to order a set of forged pistons for my 94 cobra and i need to know what size combustion chamber the gt40 cast iron heads have??? preciate the help!

[Hethj7]

This is from an earlier post I found using the search feature.

GT40

[Stangbanger86]

Hey 94snake, what mods do you have and what quarter mile times do you run???

[94snake]

Its a 94 cobra and ive got it ripped apart to the block. im gonna bore it .030 over to a 306. puttin some probe dome top forged pistons in. its got a E303 cam,edelbrock performer RPM 2 upper n lower,70 mm tb, BBK cold Air, under drive pulleys, Bassani shorty headers, bassani x- pipe, bassani mufflers, 4.10 gears, crane gold 1.7 rr's comp double roller timing chain, steeda short throw, spec stage 1 clutch, msd billet distributor, ford racing plug wires, tripple cut valve job and ported gt-40 heads......and to put that to the pavement ...a set of nitto drags 275/50/15 ... and this summer when i get some extra cash ill prolly spray it with a zex kit this summer, and a tremec TKO.

And if anyone can HELP me i need to know the cumbustion chamber size of the cast GT40 heads???

[Stangbanger86]

Hey 94Snake, according to that post it's 65.5 cc. Hey I live in Daytona, maybe one day we can get together and mess with our Cobra's. Do they have any good tracks in the state?????

[Hethj7]

Originally posted by 94snake
And if anyone can HELP me i need to know the cumbustion chamber size of the cast GT40 heads???

Why don't you take a second to read the info that was in that link I posted? If you would, you would realize that I answered your question the same day you posted it.

[94snake]

Yeh i saw that but that doesnt sound right. 65.5 cc???? i was thinkin it was like 64 or somewhere around there. I cant order the pistons i need till im positive. but uh yeh man theres a couple in Fl. Gainesville and other places.

[Hethj7]

Unit5302 was a very knowledgeable member who used to frequent these baords often. I know you didn't know that, but if you thought that number sounded off, then question it, but don't act like no one had helped you yet. In case you still question that, a quick internet search shows that number is indeed correct.

65.5 cc

[94snake]

i see that dude but on my 94-(95) the gt-40 heads have a 60 cc chamber....on the eirler models there a lil bigger....as i found out today from FORD.. (smart ass)!!!

[94snake]

Originally posted by Stangbanger86
Hey 94Snake, according to that post it's 65.5 cc. Hey I live in Daytona, maybe one day we can get together and mess with our Cobra's. Do they have any good tracks in the state?????

whats all done to your stang....year?

[Stangbanger86]

95 Crystal White Cobra, Mac H-pipe and Catback, Mac Pullies, Pro-M mass air. And some cosmetic stuff, best run so far with the limited mods is a 13.8 @ 102. Can't wait to put gears and drag radials on it!!!!!!! I'm trying to keep it as stock as possible right now so that it can get me around, but the performance is great and the reliability is awesome.

[Hethj7]

Originally posted by 94snake
i see that dude but on my 94-(95) the gt-40 heads have a 60 cc chamber....on the eirler models there a lil bigger....as i found out today from FORD.. (smart ass)!!!

Hmmm....this is interesting. I was unaware that there were two different gt-40 heads made (not talking about the P head either). I can't find real good info, but it seems like there was the GT40 that came on the Cobra and it had the 60cc combustion chamber like you said. The GT40 that came on the crate engines and the Lightning have 65.5 cc chambers. I think I will make a new post on this to see if anyone has any good info. Most of the articles that I can find just refer to the GT40, not taking into account if they are from a Cobra or Lightning.

[Stangbanger86]

Damnit, if my ex girlfriend didn't leave my cobra recognition guide on the back of my old stang I would be able to answer this one!!!

[94snake]

I went ahead and ordered a set of Ross racing pistons instead of the probes. Forged flat top 9 1/2 to 1. Also Ross plasma moly rings. It should be all back together within a week or two.

[red82gt]

Here's some more info. You'll see that the sizes are ranges rather than an exact number due to production variances. The #'s you find on othe sites are an average:

MM&FF January 1998 pg. 223
Cobra and HO marine p/n F1ZE AA 60.6-63.6cc
Explorer (1996-1997) F1ZE AA 63.4-66.4
Cobra and HO marine F3ZE AA 60.6-63.6
According to this, the cobra heads did have a smaller chamber. It doesn't give any means of identifying one F1ZE head from the other though.

On my heads (F1ZE AA's) The chambers were 61.1 cc's and came down to just over 59 with a .015 cut.

[Hethj7]

Originally posted by red82gt
Here's some more info. You'll see that the sizes are ranges rather than an exact number due to production variances. The #'s you find on othe sites are an average:

MM&FF January 1998 pg. 223
Cobra and HO marine p/n F1ZE AA 60.6-63.6cc
Explorer (1996-1997) F1ZE AA 63.4-66.4
Cobra and HO marine F3ZE AA 60.6-63.6
According to this, the cobra heads did have a smaller chamber. It doesn't give any means of identifying one F1ZE head from the other though.

On my heads (F1ZE AA's) The chambers were 61.1 cc's and came down to just over 59 with a .015 cut.

Weird. I never was aware there were so many variances in these...I just thought it was the GT-40's and the GT-40P's. I don't ever recall anyone bringing this up on MW before, or did I just miss it?

[red82gt]

It seems that any good info I've found on GT-40 heads is from 1998 or older. after that, it's the same internet stuff from the same source that gets regurgitated all over the net. There's a chart with footnotes and stuff too.
I'm just wondering, if I were to scan it and post it, would I be in violation of copyright laws?