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George T. Schmidt stamp dies were gaged by what they measured from the top point to the bottom point of the character on the die. The impression they made on the pad would measure taller, depending on how hard the holder was hit, as each character created a bevel as part of the impression which made the stamped impression measure slightly taller than the character on the die.
It's my belief that the '65 JG shows the correct George T. Schmidt die sizes - 3/16" for the engine plant stamp, and 5/32" for the assembly plant VIN derivative stamp.
John is absolutely correct. The drawing below shows the face of a typical Schmidt single character stamp as used at the assembly plants.
If a stamp character is hit just hard enough to leave a slight impression on the block, the dimension of the impression would match the dimension of the character on the stamp. If the character stamp is hit harder, the character is driven deeper in the block and the impression becomes taller and wider.
It's difficult to measure the height of only one character but if you do a little math, you can calculate the length of a complete seven character package.
There's a long discussion in the archives that will help explain why the character size can be determined by the length of the seven character package. If I can find it, I'll post the link.
The 3/8" dimension used in the drawing below is only used as an example.
Last edited by Michael H.; September 23, 2009, 06:07 PM.
..... It's difficult to measure the height of only one character but if you do a little math, you can calculate the length of a complete seven character package.
There's a long discussion in the archives that will help explain why the character size can be determined by the length of the seven character package. If I can find it, I'll post the link.
The 3/8" dimension used in the drawing below is only used as an example.
Thanks Michael --- to the rescue, as always . That was the main thrust of my original post, which was missed, IMO, by the replies that fixated solely on height. Using C2's as example, measuring the gang impression length of 7 standard characters of known die width would be seven times more accurate than trying to measure the height of any single one (whether VIN or assembly plant applied). Of course an allowance would have to be made for the last letter of the engine code (eg. I vs M), or for the last die being applied separately. (ie. the rarer versions of the 1965 'H' series, or overstamps). Still, one heck of an easier job (even for laying a ruler on the pad) than trying to figure out a 1/32nds difference in imprint height.
I'm not saying we should ignore the height(s); only that it become secondary (ie just a visual) check, versus a measurement of the length(s).
Look forward to the link to that thread on length-based test.
P.S. Bill C. -- thanks for that catalog page (I was still composing my post when you posted yours) Neat; can this be used for the "football versus watermellons" chart ? :-)
Last edited by Wayne M.; August 11, 2009, 09:26 AM.
.....If a stamp character is hit just hard enough to leave a slight impression on the block, the dimension of the impression would match the dimension of the character on the stamp. If the character stamp is hit harder, the character is driven deeper in the block and the impression becomes taller and wider.
It's difficult to measure the height of only one character but if you do a little math, you can calculate the length of a complete seven character package.
Thanks, Michael -- your link to the 2005 thread explained it much better than I could.
So, the big question is: why do the technical manuals continue to focus on character height when length of the gang group is as important ?
Per your "hit harder" comment, I've always thought that the Vol 20 # 4 (Spring 1994) RESTORER back cover, with pic taken by John Amgwert is a good example in character impression becoming taller and wider (on one end) and lighter on the other, in this slightly angled "whack".
Per your "hit harder" comment, I've always thought that the Vol 20 # 4 (Spring 1994) RESTORER back cover, with pic taken by John Amgwert is a good example in character impression becoming taller and wider (on one end) and lighter on the other, in this slightly angled "whack".
So, the big question is: why do the technical manuals continue to focus on character height when length of the gang group is as important ?
Per your "hit harder" comment, I've always thought that the Vol 20 # 4 (Spring 1994) RESTORER back cover, with pic taken by John Amgwert is a good example in character impression becoming taller and wider (on one end) and lighter on the other, in this slightly angled "whack".
Good picture Wayne. There sure is a difference in size between the deep left characters and the shallow ones on the right. It looks like the far left character is probably 1/16" taller than the character on the far right.
Below left is another (poor) example of the difference in height of a character, depending on the depth of the impression in the metal.
On the right, an actual character stamp that shows the bevel.
Last edited by Michael H.; September 23, 2009, 06:07 PM.
i want to thank all of you guys for your input on the matter. my engine builder is going to try to leave the origional stamping. if not its going back just like it is (quarter three sixteenths) thanks again tom
i want to thank all of you guys for your input on the matter. my engine builder is going to try to leave the origional stamping. if not its going back just like it is (quarter three sixteenths) thanks again tom
Tom,
Have you measured the overall length of each seven character package? Just wondered what they are.
mike i asked the folks building my engine if they would do that . at that time the block was on a jig or machine where they couldent reach the pad with calipers or what ever but i will do it soon as i can tom
. That was the main thrust of my original post, which was missed, IMO, by the replies that fixated solely on height. Using C2's as example, measuring the gang impression length of 7 standard characters of known die width would be seven times more accurate than trying to measure the height of any single one (whether VIN or assembly plant applied). Of course an allowance would have to be made for the last letter of the engine code (eg. I vs M), or for the last die being applied separately. (ie. the rarer versions of the 1965 'H' series, or overstamps). Still, one heck of an easier job (even for laying a ruler on the pad) than trying to figure out a 1/32nds difference in imprint height.
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