Engine Block Date Code Question

[Daniel R.]

There's a 62 for sale on the internet that I have a question on regarding the engine block dates. The car is # 5744 which makes it a January 62 built date. The engine block stamping pad reads 2105744 F1130RF The engine block casting date reads L 14 1
To me that means that the engine block was casted on December 14 1961. However, with the block stamped F1130RF means that the engine was assembled on November 30 1961 Which is prior to when the block was casted. Any ideas from anyone?
Thanks , Daniel Ross N.C.R.S. # 12918

[Harry S.]

Re: Engine Block Date Code Question

What letter was not used when dating blocks, M is December.

[Edward J.]

Re: Engine Block Date Code Question

Dan, The casting date of Nov. 14 , (L= November)and build date of Nov. 30th sound okay. (I) was not used

[Edward B.]

Re: Engine Block Date Code Question

For cast-in date codes on GM-produced iron and aluminum castings (engine blocks, heads, intakes, water pumps, etc.), the letter "I" was used for September, and the last month of the calendar year (December) was the letter "L". For stamped-in date codes on GM-produced components (alternators, distributors, starters, etc.), the letter "I" was not used - "I" was skipped, and "J" became September, with December being "M".

ARTICLE FROM JOHN HINCKLEY

Post a picture of the pad and the date casting.

Ed

[Harry S.]

Re: Engine Block Date Code Question

For cast-in date codes on GM-produced iron and aluminum castings (engine blocks, heads, intakes, water pumps, etc.), the letter "I" was used for September, and the last month of the calendar year (December) was the letter "L". For stamped-in date codes on GM-produced components (alternators, distributors, starters, etc.), the letter "I" was not used - "I" was skipped, and "J" became September, with December being "M".

ARTICLE FROM JOHN HINCKLEY

Post a picture of the pad and the date casting.

Ed

I'm not sure I agree with that. I've held in my hand a 63 Master Cylinder with a date code of M.

The picture is from Jon Rubel.

[Edward J.]

Re: Engine Block Date Code Question

I stand corrected the letter (I) was used. So there is something going on with the pad stamp. I am bowing out as this need to be straighten out by someone who Knows casting dates. I did a Google, and it will show the letters and there months.

[Mike E.]

Re: Engine Block Date Code Question

If the numbers you list are correctly cited, there is a significant issue. L is definitely correct for December, not November, 1961.

[Daniel R.]

Re: Engine Block Date Code Question

Hello Mike , That's what I 've always thought that L was for December on engine blocks. It's good to hear it from an expert.

[Daniel R.]

Re: Engine Block Date Code Question

Hello Edward, According to the NCRS publications( I ) was used for September on engine block castings. I found it on page 85 of the 53-67 Corvette Specifications guide (pocket size) Thanks for your input, Dan

[Daniel R.]

Re: Engine Block Date Code Question

Hello Ed, I am trying to post a picture , but it don't seem to want to go through. I'm new at posting on the NCRS site. Thanks Dan.

[Daniel R.]

Re: Engine Block Date Code Question

Block stamp.jpgDate casting..jpg Here are the pics of the casting date and the engine block stamping pad.

[Richard M.]

Re: Engine Block Date Code Question

If the numbers you list are correctly cited, there is a significant issue. L is definitely correct for December, not November, 1961.

I agree. Engine blocks use the letter "I" for September. Maybe some other foundries did not use "I" as Harry's example showed of the Master Cylinder. Good info Harry. Amazing we can learn new things after all this time.

Here is the photo of the pad at a more readable angle. IMO it is NTP, and then some. Something's fishy here. I think someone got their L's and M's mixed up and hit the wrong button on the pad. Those simulated broach marks are just a tad conspicuous and would give me reason to negate this pad. And if I'm not mistaken, aren't the assembly stamps typically very close to the edge of the pad?

The only other thing I could think of is that there was a typographical error by Mr. Engine Stamper that day in Flint, and it should have been F0II3RF(Jan 13), but that's reaching isn't it?

Block stamp_1961_.jpg

[Terry D.]

Re: Engine Block Date Code Question

Run Forest Run!

[Edward B.]

Re: Engine Block Date Code Question

I agree. If those aren't an optical illusion, then someone did a bad job at recreating the factory broach marks, so the pad is suspect. Would it be possible to get a higher resolution picture of the stamp?

As for the "M" master cylinder...

There's one exception to the GM dating convention that has been observed. Some BLOCKS have been seen with "M" cast codes. Research by the Saginaw Metal Casting Operations of GM Powertrain Division has found that these "M" codes are not date codes, but actually a foundry code used to identify parts that were made to evaluate a casting process change. After evaluating the parts, the blocks would either be destroyed or released into production. There is no way to determine the date an "M"-coded block was poured.

I don't know about master cylinders, but this "could" be the same thing.

Update: I asked John Hinckley about the "M" master cylinder code, but he wasn't familiar with the foundry practices at Delco-Moraine and didn't know if they used the same protocols. He believes that most of their castings were done at the Central Foundry casting plant in Defiance, Ohio.

So it's a mystery!

Ed

[Leif A.]

Re: Engine Block Date Code Question

Gents,
What am I missing here. Weren't the "I" and "1" used interchangeably on the line. Hence "II" could be November, as well as, "11" Therefore, a build date showing of November 30th?