546/2 engine "case casting number"

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Tom Coughlin
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546/2 engine "case casting number"

#1 Post by Tom Coughlin »

I decided to upload my data to the club database and after looking at my casting number 8770 (Porsche calls it the internal number) just left of the engine type 546/2, using Harry Pellow's formula generates a date of 1956 v the May build date for my car.

If you have a 546/2 engine, please let me know if your "case casting number" (ccn) gives you a correct build date for your car. Harry's formula is ccn x .00011 plus 55.55. The resulting number first two digits equal year, and the other digits x 12 gives month.
For example using ccn 1999, multiply 1999 x .00011 plus 55.55 = 55.76. The first two digits are the year and 76 x 12= 912 or Sept. 1955.


UPDATE. I have just received numbers on several other 546/2 engines including engine 35067 with ccn 9182. Based on five other engines, it is clear that ccn 8770 is the right number for the original engine case of my May 1955 car. Therefore, don't worry about sending me your ccn unless you are bored, etc. Tom
Last edited by Tom Coughlin on Thu Oct 27, 2022 8:05 am, edited 1 time in total.
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Jacques Lefriant
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Re: 546/2 engine "case casting number"

#2 Post by Jacques Lefriant »

Hi Tom
i would think the proper nomemclature would be internal no. that is the after maching: the internal to Porsche not the case was sequentially added to the machined castings. sometimes like the Carreras they went back to 1 for the different types of 4-Cams since they were machined on a different set of machines to different configurations. when the cases were populated the serial no and type were added. i guess the head of the assembly department kept this info in a notebook. fortunately for the curious that no was usually added to the fuel log when the initial fuel was added for a test drive. Harry did a curve fit to the data that he observed.
j
Last edited by Jacques Lefriant on Thu Oct 27, 2022 9:52 pm, edited 1 time in total.
 

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Tom Coughlin
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Re: 546/2 engine "case casting number"

#3 Post by Tom Coughlin »

I agree that the proper nomenclature is "internal number"-that's what the factory shows it to be in a picture in the front of the 1954 Service Manual.

Harry called it "case casting number" so I guess we are forced to live with both names for a long time.
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Re: 546/2 engine "case casting number"

#4 Post by Donald Zingg »

tom coughlin wrote: Thu Oct 27, 2022 8:15 am Harry called it "case casting number" so I guess we are forced to live with both names for a long time.
Ditto the misnomer commonly applied to Porsche Type 356 sports cars built between 1949 and 1955 (and to this little corner of the Forum). I've never heard anyone refer to a 356A Speedster as a "'post-356" car. All we can do now is embrace it and be happy ;)
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Re: 546/2 engine "case casting number"

#5 Post by John Brooks »

Who made the flags, I need a set….
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Re: 546/2 engine "case casting number"

#6 Post by Martin Benade »

And really how sensible is the term “internal number”? It clearly is external.
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Re: 546/2 engine "case casting number"

#7 Post by Jim Wayman »

Looks like another "fail" for Harry's formula. Engine 34022 has internal (CCN) number of 7741. That would indicate a 1956 date when the production date is actually December 1954.
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Re: 546/2 engine "case casting number"

#8 Post by Jacques Lefriant »

Hi Martin
it is Porsche speak meaning it is a no. for Porsche factory use only.
Hi Tom
the formula was not used by Porsche it was a linear curve fit to estimate the date base on the data available that had a lot of scatter.
j
 

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Re: 546/2 engine "case casting number"

#9 Post by Martin Benade »

I was just being silly about that. Internal does make sense.
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Re: 546/2 engine "case casting number"

#10 Post by Tom Coughlin »

Jim: I have to believe that Harry's formula was never developed with 1955 and earlier engines in mind considering that you have to add 55.55 to the product of the "internal number" (Martin: that's an inside joke -LOL) multiplied by .00011. No matter how low the internal number, it can never result in a number and date earlier than 1955 (and most likely 1956).
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Re: 546/2 engine "case casting number"

#11 Post by Spencer Harris »

tom coughlin wrote: Fri Oct 28, 2022 3:09 pm Jim: I have to believe that Harry's formula was never developed with 1955 and earlier engines in mind considering that you have to add 55.55 to the product of the "internal number" multiplied by .00011. No matter how low the internal number, it can never result in a number and date earlier than 1955 (and most likely 1956).
I think you're spot-on, Tom. My '55 case has internal no. 8765 (May 10, '55 Kardex date), and like yours the formula yields a MY '56 date - no matter how many decimal places you carry it to.
55 Int No conversion.JPG

Using Harry's formula for these Aug '57 internal numbers yields late July '57, and the final inspection dates are all early August.
Copy from Porsche Production Book.jpg
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Re: 546/2 engine "case casting number"

#12 Post by Jim Wayman »

Tom

That was my initial thought when I ran the formula for my engine. I remembered how down Harry was on the early engines and thought that his formula was probably for his "favorite" engines.
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