[GRX]

Does anyone know what these casting number mean? Typically on the front passenger side of the block. The "GM E" is from my early '67 428 4-bolt block. Never seen that one before.

[Half-Inch Stud]

...had a very-early dated 1967 428 4-bolt where the only CASTING ID was GM E, and the block part #. I assumed it was GM Engineering. Who knows..
Taht block sits on someone's 66-67 GTO now.

[The Boss]

GM = General Motors

[Rocky Rotella]

I've heard that it's a mold or batch number.

[JLHarper]

Originally Posted by Rocky Rotella

I've heard that it's a mold or batch number.

Pete McCarthys book says same basically: foundry casting line #

Wasnt the "E" after GM a revision number of engineering drawing?

It was mentioned on another thread too. I'll see if I can find.

Originally Posted by The Boss

GM = General Motors

or ......Govnt Motors..... if you ask in the CH PeaNUT Gallery .....

Jeff

[bryansMtngto]

from what i have found it should refer to the Mold Id that was used to create the block.

[GRX]

Makes sense about the "E" standing for engineering. My thinking is these are first run castings, before they went into general mass production. This early 428 exhibits no visible casting shift and has the more complex mold parting lines. It also came with the factory re-balanced 421 Armasteel crank. Pontiac using up old stock.

These early blocks should be very strong. Both high nickle and superior "skeletal structure". More on this in a block thread from a few years ago.

(whole thread)
http://forums.maxperformanceinc.com/...d.php?t=490695

(posts with images I submitted concerning the molds)
http://forums.maxperformanceinc.com/...&postcount=156
http://forums.maxperformanceinc.com/...&postcount=157
http://forums.maxperformanceinc.com/...&postcount=158

[yahooskidoo]

Found this one on ebay says it's General Motors Experimental
http://www.ebay.com/itm/270890629078...84.m1438.l2649

[GRX]

Originally Posted by yahooskidoo

Found this one on ebay says it's General Motors Experimental
http://www.ebay.com/itm/270890629078...84.m1438.l2649

$2,000. No wonder they got zero bids. So far I have been told 'evaluation', 'engineering' and 'experimental'. That last one seems the most unlikely. Curious what the numbers mean. Like the 10 above. Undoubtedly a foundry code of some sort. Judging from my experience with plastic injection molds in my tool & die machinist apprenticeship days, could be the number of runs on that particular mold? Don't think Pontiac had 10 foundries. Could be wrong.

[edit] - Seems my suspicions were right. The Year One page has this listed as "The foundry line casting".
http://www.yearone.com/updatedsingle...ontengid1.html

High Performance Pontiac has this to say:
"In addition, usually adjacent to that number is a large "GM" followed by one or more numbers (GM10, for example). A former Pontiac foundry employee told me the series of digits was used as an internal lot code to denote foundry batching".
http://www.highperformancepontiac.co...a/viewall.html

[yahooskidoo]

I think it ended early, someone called him and bought it probably.

[Formulabruce]

I was told long ago that it was the "MOLD" variant that the molten metal was poured into, to make that "core". There were many of each variant, and some identical blocks could have different variant numbers as molds broke, leaked, etc.
This was from a guy who worked at a Chevy foundry plant, near Flint, though.

[GRX]

Looking again at that eBay block I wonder if it is a virgin casting. And the casting date is really early = Sept 12 1967. The one I have is January 17 1968. Leads one to wonder how long they cast these "E" blocks.

[Brian Baker]

I read somewhere, sometime, that the "GM E" meant "General Motors Experimental" and that the R.A. V blocks could be identified in this manner, but then I found my garden variety '68 casting 428 block I once owned had these letters cast into it as well.

[tom s]

true engineering items had DS numbers.My alu V block,early alu 389 blocks,alu heads and RA V heads had them.Even have intake manifolds with them.Dont think the E is for engineering.FWIW,Tom

[The Boss]

Could E have stood for Pontiac?

As in:

A = Cadillac
B = Buick
C = Chevrolet
D = Oldsmobile
E = Pontiac
F = GMC

Just a WAG.