The date stamp area looks to be filled with some grime. I wonder if this would look different if this area could be cleaned up better.

Ratbox,

The area you are speculating contains a '3' looks to me to be a casting defect in the raised line between the week and year. I will crawl under my cars and see if I can make this out of '73 and '71.

Great Fryardds ,

I do not know about the earlier cases. But on the 1979 I posted (obviously a replacement case , and I have a 77) , the week & year numbers seem to be cast in & protrude out from the case. I believe when you look at one of these earlier cases. I don't think they are stamped . I think they are too small for that , I believe they would be from a small removable plug that goes into the case casting mold that has the numbers corresponding to each week of a year in the plug.

Actually when I look harder at Mattia's . I see I was fooled, the circle is a depression and the bar and small numerals are raised up from the depression circle. Just like on the later ones.

In the bar of mattia's casting date . What I thought looks like a 3 , is probably slag as you say...that makes more sense and aligns with the later cases I am looking at. And on mattia's case though the material under the bar seems to all be the same color.... not filled with any grime (and could not be if the numbers protrude as I think they do) . The last two digits of a decade (signifying casting year) do not seem to be there. But that is just what my eye sees. I would think normally a year should be there. I will try to look at any others I can , & take photos if possible.

Unfortunately if your looking at motors with exhaust & tubes installed , getting a close look is not easy. Obviously a photo is even more difficult.

Yeah, I raised the rear of the '71 and it is as you describe, very difficult to read the date marking and is impossible to photograph.

I used a dental mirror (I've got a few of these around;) ) to view the mark. The circular depression w/ a center bar is the same, but that is where the similarity ends. Below the raised center bar are 4 tiny protrusions organized randomly it would appear. There are 2 tiny raised symbols above the bar which don't look like numbers but I don't really know what they are. This is the right halve of the engine, which is a 3R casting.

The other side is truly impossible to see well, even with a mirror, but I could tell it has 5 raised protrusions below the bar. This halve is a 3R casting also.

Someone with access to a engine case or just one out of the car will have to help out. I am very curious now about what this mark means.

It is obviously a system of dating that is prior to the one that was in effect by 1977 (the example I have, that yes I had to use dental mirrors also to examine as it's a complete motor with auxilarys attached). If mutiple examples from each year are examined and chronicled. Then not only will we be able to figure out when the switch was made from one type of marking system to another. But also should be able to figure out the legend to decode the pre-numeral type.

Ratbox,
Double cheking I can confirm what you thought looks like a 3 , is slag. There's no digits for decades....so no way to understand my engine block belongs to (probabily is 7R from non carrera 2.7).

Now I have all engine parts from carrera 2.7 (MFI, heads, cylinders, cams) but not the original 911/83 block: how you evaluate the car value from originality point of view?

Do you suggest me to search for original 911/83 engine block? What can be the right price if any chance to find one in original and mint condition?
Thanks all of you for your assistance and patience to follow my case.
mattia

mattia,

If you wish to get a set of 7R cases , that were originally built as a type 911/83 motor by the factory for added value to your car. Then the only one to logically get is another 1974 MY set.

As to cost ? I can only tell you that I noticed last year on the early S forum, that someone posted and sold a complete 1974MY 911/83 long block (in unknown internal cond.) . They were asking 6500 US. I do not know what the final sale amount was. But i'm sure that amount , or very close.

That is only one sale , so it does obviously not show a pattern for determining value. And one item can be worth more or less from one person to another (needs and wants).

Buying a 2.7 and have a question on the case number
 

Hi, I'm buying a 2.7 rebuilt motor. As I understand it it came from a 74 911. The case number that was given to me is 9141933, but that seem not to be in the range from the research I've done. Can anyone tell me if this is a valid number? The motor is assembled and packed already.

The engine serial number should start with a '6', not a '9'. Second digit is for the model of the car, and third is the year. Last four digits are the sequential numbers for the engines made for that particular model.