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Discussion Starter · #1 ·
O.k.. I have a 2000GT and came across a smoking deal on a complete 4V head set for $600. Includes everything all the way to the C.O.P.'s So my question is will they fit on a my 4.6? Are the blocks all the same between the 2V GT block and a 4V Cobra? I know I need the intake as well and can get one from the same guy for another $350 so I need to know. Also, what kind of performance gain can I expect? I'd assume I'll need a tuner, yes/no? Anything else I am not thinking of?




Richard
 

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Cobra heads

Yes the Cobra heads will fit on your GT, BUT you would be a lot better off sticking with your stock heads and getting them ported and polished. I'll tell you why. The swap is very difficult and can actually end up costing more than buying a whole Cobra engine. Besides the heads, you'll need, cams, valvetrain, computer, wiring harness, timing chains, front cover, forged internals to handle the extra power and rpm's, and a ton of other odds and ends. When all is said and done, the money you would have to spend to put the Cobra heads on wouldn't even remotely come close to being worth it unless you have some fierce goal in mind like a 7 second mustang. With your stock heads ported and polished, you'll have PLENTY of air flow for anything you want to achieve with a street legal mustang.
 
G

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also in addition to what was posted above, todo the DOHC swap.... in addition to the heads and intake and the above mentioned parts, you'll also need DOHC exhaust manifolds and all the coolant hoses, tubes, thermostat housings and more.....
 

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Discussion Starter · #4 ·
The heads are complete already with cams, valves, rocker arms and everything. They were removed from a Cobra and just need to be bolted right back on.
I just needed to know what else I would need to bolt them to my block and what kind of power gains I could expect?


Richard
 

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The heads are complete already with cams, valves, rocker arms and everything. They were removed from a Cobra and just need to be bolted right back on.
I just needed to know what else I would need to bolt them to my block and what kind of power gains I could expect?


Richard
Randy and I listed out every single component you MUST have in order to install the Cobra heads on your GT, they're not recommendations. Plus if the heads came with "everything", you'd be getting the entire assembled Cobra engine. You need to understand that a Cobra motor makes most of its power UP ABOVE the GTs redline. How and why? The Cobra motor is a long block and your GT has a short block. This means that if you simply bolted on the heads and did the swap without ever single component we listed including ALL UPGRADED internal parts and a new crank (which is THE KEY component that you're missing) I would be very surprised if you saw more than 5-10RWHP peak gain. The peak would never be reached with the stock 2v rev limiter and you would lose a good amount of torque down low. You need to be able to hit 7000rpm constantly in order to utilize the Cobra heads. Compare a stock GT to stock Cobra dyno chart and you'll see the GT makes more torque down low due to the small port size for better velocity. Plus, if you're not already, you have to run 91 octane gasoline or else it'll run like crap and you're gas mileage is going to drop to about 16mpg.
 

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Discussion Starter · #6 ·
well then...I'm glad i asked. Sounds like it is not just a bolt up with a couple of parts changes. I just look into porting and polishing my current stock heads.


Here's another question for you guys though. I am currently running 245-45-17 tires on the stock suspension. I am going to buy a new set of tires and want to change the look/stance of my ride. I would like to go wider but I don't know how wide I can go before I run into interference problems? Someone suggested 275 series tires would work is that correct? Can I go any wider, say 315's? I would also like to add some lowering springs at the same time as well. With that in mind, how wide can I go with lowering springs? I am figuring the spring s to drop it 1 1/2" in the back and 7/8" up front. Based on the dimensions listed by the spring manufacturer.
Oh yeah, I have Cobra 5 spoke rims, not the stock rim.

Any ideas on this?


Richard
 
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