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Last Post 24 Nov 2011 09:40 PM by  snaponbob
cobra replacment head question
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mobil302
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23 Nov 2011 10:25 PM
    I have a question about the update/backdate rule for sn95 mustangs. I have been asking around and searching online for weeks, but can't find a answer. My question is, can you use GT40x aluminum heads on 95 cobra? I have read everywhere that you can use the gt40x heads on a 351 cobra r spec motor, because the gt40 iron heads and gt40y heads are out of production years ago. I tried calling the local ford dealership for answers. I asked the man on tje phone about my gt40 iron heads and of course he told me they stop production on the heads. I asked him about a replacement head for the cobra irons. The man suggested the frpp gt40x heads. I asked the man if the part number for the gt40 iron was the gt40x. He told me no. So I asked again what cylinder head is the replacement head for the 95 cobra if the irons ar e no longer in production. The man replied back, gt40x. Now im confused.
    snaponbob
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    23 Nov 2011 11:06 PM
    COMPLETE engines can be swapped via update/backdate, but from cars on the "same line" in the class. Intake and exhaust are "free", but not engine components. Your options are repairing or reconditioning the head, or finding one on a forum or ebay.
    mobil302
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    24 Nov 2011 12:46 AM
    I was just woundering, because the 93-95 cobra had the same part numbered gt40 iron heads as the 95 cobra r 351
    snaponbob
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    24 Nov 2011 09:40 PM
    mobil302 wrote:
    I was just woundering, because the 93-95 cobra had the same part numbered gt40 iron heads as the 95 cobra r 351

    Okay, this can get "challenging". If the 93-95 Mustang Cobra is on the same line as your car, you MIGHT be able to swap components. BUT, they are pitfalls. First, other than the heads, the engines would have to be identical. Same pistons, cam, all that good stuff. Same same same. At that point, the case could be made that the ONLY difference was the head, and thus you are duplicating a 93-95 engine, but not swapping a whole engine. Again, this would potentially fall under the update/backdate only if the cars on the same line.

    Is this viable? Yes. Oodles of years ago I raced a 77 Civic in D/SP. If had what was called an EB2 engine. I found that an EB3 engine could produce some more power. My choices were swap an engine (could not afford that pre-internet), keep the EB2, or convert it. I had found that the ONLY differences were the pistons and head (put the EB3 pistons and head in an EB2 and you would have an EB3.) I sent a letter to SCCA with the documents and they said it would be okay. You will have to do the homework on your engine to see if you would be legal.

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