[jtillery]

I am trying to figure out what has been done to one of my 5.0 parts cars. I was told the car had GT40 heads, but I am almost positive it doesn't. We pulled one of the valve covers off and it has a non-roller cam and the only casting number I could find on the heads is 4G28. There was also 12J0 10 stamped on one of the heads. Does anyone have any idea what the heads are from? Is there any way to tell what year/model the block came from? I didn't find any casting numbers yet, but haven't looked hard.

[JBIGBOOTSY]

GT40sand gt40ps have 4 bars at the front and rear of the head cast into them twards the intake side of the heads.

[jtillery]

There isn't any bars on these heads at all, I was doubtful they were GT40, but it seemed like a very strong running engine, so I am trying to decide if I should use them in my build. GT40 and GT40p are definitely ruled out. They also have the same spark plug angle as the stock Mustang heads.

[neverfastenough1]

Anymore numbers on the block? Those numbers didn't help at all on the head. Try to find a number starting with a letter.

[jtillery]

I am going to go over to my shop tonight or tomorrow morning and scour the block for numbers. Is there any particular place they normally put them? The car is a 92 5.0 hatch, I am assuming the block is the original 92, and the heads are off something older. It is possible to run a roller block with a non-roller cam with the appropriate mods? It has a nice lope to it, so it has some type of aftermarket cam installed.

I figured out what performance shop supposedly did the work on it, so I am going to call them tomorrow to see if they have any records on it.

[neverfastenough1]

http://www.classicmustang.com/casting_numbers.htm

[jtillery]

I called the shop that supposedly did the work on the car, they said they couldn't find the records but would keep looking. I doubt I will hear back from them.

I did find the casting number / date code on the block, only problem is I left the piece of paper I wrote it on at the shop. It started with F1, which I believe designates it as a 91, so it should be the original block (car was manufactured Jan 92).

I attached a quick drawing of the marking I found on the head. The drawing is supposed to show the head with valve cover removed, and the blocks are lifters. The info I found makes it seem like the actual casting number is on the bottom side of the head. Is there any well to get a general idea of what they are without removing the head though?

[neverfastenough1]

Yeah, you still got me on the head. Thats the number you found under the valve cover? Yes the f1 should mean its a 91 block.

[jtillery]

Yes, the number was under the valve cover. It seems like I will definitely have to pull the head to get the actual part number to identify it.

I have another 5.0 donor car that has GT40p heads and GT40 upper/lower intake, that I was planning on using for my project but I got an offer that is hard to refuse so I think I am going to sell it. I eventually plan to upgrade the heads and intake on this engine, but I was trying to figure out if I should plan to do it right away, or run for awhile as is. The upper/lower on this engine is the stock Mustang and has had some porting work. Even though I have no idea what the heads are, my assumption is they must flow better than the stock heads since it is unlikely someone would go to the trouble to swap them and the cam if they didn't. The car was wrecked, so I could only drive it up and down my street a little, but it seemed to run hard. I do plan on putting my Paxton Novi on it though.