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GT40 Tech - Engines/Induction/Exhaust Motors and engine related - right here!

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Old 12th August 2017, 09:03 PM   #1
A Tenth
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Original GT40 Mk II Heads?

Had oil blowing out the valve cover gaskets on my Contemporary Cobra on to #5 and #1 plugs. So, I decided to clean the mess up, and replaced the valve cover gaskets on both sides.

I had been told by the person who sold me the Cobra that his father, a racer, had bought the motor (have receipt) from Holman Moody, and that the motor was probably worth more than the car. But, I never pulled the motor apart to check the details.

As it turns out, the head markings were: on the outside, an "X" on one end of the head; on the inside along the edge of the head below the springs, C5AE, a cast date of "1-22-65", PROCESS-FD1, 6090H; between the #6 and #7 pushrods headed into the motor "202A"; and then inscribed on the flat portion of the head where the valve cover gasket would go "79CC SRNJ" on side and "80CC" on the other side.

Can anyone confirm that in fact this was a 427 (well at least he heads) that may have been built to use the MKII's?

If so, may pull the current 427 in the GT40, and replace it with this Cobra motor.

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Old 12th August 2017, 09:34 PM   #2
A Tenth
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Re: Original GT40 Mk II Heads?

May have at least partially answered my own question. Found a thread where Jay Cushman indicated the aluminum heads I mention were for Cobras whereas the C6 aluminum heads were for the GT-40s. However, Mustangtek site shows the heads I mention were for the Shelby GT-40 program, but who knows where that data came from.

The motor I have in the GT-40 now does have the NASCAR crank and NASCAR rods. Anyone know if the GT-40s that raced used the heavier crank and rods like the NASCAR 427's used for high RPM long haul racing?
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Old 13th August 2017, 10:45 PM   #3
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Mike Drew
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Re: Original GT40 Mk II Heads?

I believe they are called "Le Mans rods" which probably tells you something.

But I don't have any expertise in this matter.....
Mike Drew, Vacaville, CA (
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'72 De Tomaso Pantera, '66 Contemporary 427 Cobra, '66 Shelby GT-350 clone, and gearing up for a Superformance Mk 1....
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Old 14th August 2017, 02:23 AM   #4
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Re: Original GT40 Mk II Heads?

The 79CCSRNJ and 80CC will be the volume of the combustion chambers of each head. those engines in the GT40's only ran 10.50/1 or 10.75/1 in Europe to avoid fuel octane quality issues.
RODS: Le Mans is normal width and weighs 833/845 grams p/n C5AZ-6200-D for 427
...........Same rod for 1969 SCJ 428, p/n C9ZZ-6200-A but with shorter cap screw bolts.
...........Nascar wide rod, 936/1036 gram's, p/n C70E- 6200-A
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cobra, cover, head, motor, valve

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