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Old 08/27/2005, 08:01 PM   #1

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X code or S code

Ok everyone chew on this for a while and tell me what you think. Bought this X code 2 weeks ago and have preceded in yanking out the motor yesterday for a rebuild. I have had a few questions to a few members on this site pertaining to this motor as things were not adding up to be a x code motor. First there was the 4v and the S intake manifold. Next I yanked out the motor and on the back of the block was the VIN numbers, hurray it is a numbers matching block, OK so I take the motor apart and there is the large X in the valley, not sure what this means but I thought someone has said it is the higher performance block, is this right. OK next tear it down, take out the pistons and on the pistons are 390 4v. thats about it, can not tell by the cam as it was replaced in a partial rebuild a couple years ago, ok you might say they changed the pistons but I do not think that is feasable, would not make sense. So my best guess is in 68 when they had the strike some replacement worker or group slapped a S code motor in a X code car, quality control not being what it is today whew what do you all think of this senario , lay it on me Chuck ??? ??? ???
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Old 08/27/2005, 08:46 PM   #2
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Re:X code or S code

wasn't it just the intake and carb that changed from x to s code?

2V compared to 4V
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Old 08/27/2005, 10:05 PM   #3
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Re:X code or S code

Both engines used the same crank, pistons, rods and oil pump. The difference was the heads, cam (428CJ), Intake, and 4V Carb (600CFM Holley). Even my GT motor has an "X" stamped in the oil galley. Many folks have mentioned checking the bore to determine a GT motor but, since both engines used the same pistons that really doesn't make sense. The best check is the camshaft. That's why it is so easy to actually turn your "X" code motor into a GT motor. A few swaps and your there.

Don ;)
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Old 08/28/2005, 05:42 PM   #4
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Re:X code or S code

I agree with Don, the X-Code and S-Code were nearly identical excluding the cam, fuel pump, and obviously the carb and intake. Everything else was the same.

If you are going to take the car back to the 2-V setup you need to locate the correct intake. Two different versions were made, C7TE-9425-G was equiped on cars produced before 1-9-68. The C8TE-9425-A was after
1-9-68. Both numbers are the casting number, these were very common on the F-Series trucks that had the 352, 360, and 390's.

The correct carb is a C8OF-K. Hope this helps, good luck.
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Old 09/08/2005, 05:28 PM   #5

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Re:X code or S code

The heads are different in the X-code. The heads were not drilled for smog,-air injection. Both are C8AE-H and 14 hole exhaust. All 390 GT's and 428cj's came with air injection in 68. So in the X-code is the only non-smog pump car. Date codes should be within the month.
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Old 09/08/2005, 05:41 PM   #6

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Re:X code or S code

Oh yea, and the X in the valley means nothing. Most 390's have this. It is often mentioned as "high nickel content" Although their is no evidence that this is true. just an X in the mold.
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Old 09/09/2005, 10:50 PM   #7
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Re:X code or S code

I have also seen a different air cleaner snorkle that is used on the X code 390 cars. It is different from the 390GT, it is unique, and relatively hard to find. Instead of angled forward, it is angle rearward, very similar to the 428CJ and Boss 302 snorkle - and is often mistaken for these. The difference is the angle piece is angled sharper and shorter in length, and the mounting base is the normal non-high performance wide bolt spread pattern, so it can mount to most any Ford air cleaner. If you try and mount it to a true 428CJ or Boss 302 air cleaner, the holes will not line up.
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Old 09/12/2005, 07:11 PM   #8
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Re:X code or S code

Do you have any pictures of the snorkle you can post? I can't say that I've ever seen one you are describing. I have seen a couple 390 cars with a rather long round snorkle. Both of those owners claimed it was original, they were San Jose cars, maybe 67's.
(I do not have any digital pictures of those snorkles)
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