Just received my 327 short block from the shop, the good news is it looks great, the bad we had to deck due to rust problem on block, its a long story. Any suggestions on how to restore numbers or who can stamp in the LI, NY area.
Thanks to all, without the help of the people on this forum I would not have gotten this far on the restoration.
Charlie F
66 Coupe

 

It is extremely difficult to duplicate the characters (font, size, and depth of penetration) and pass NCRS judging. The other issue is that a block decked in the field will have circular tool marks rather that the linear marks that were created from the OE broaching operation, so even if you manage do do a good restamp, the circular mill tooling marks will make it obvious that it's a restamp and not original.

Bottom line is that if the block is decked enough to remove all traces of the OE character stamping, I don't see any point in trying to replicate them, but at least the block casting number and date code can be verified. Anyone with any experience looking at stamp pads will be able to tell it's a restamp. I hope you at least took a photo of the pad before the block got decked!

Last night I went to our Friday night Redondo Beach cruise at King Harbor and ran into an older gentleman who has a '23 T-bucket that I had not seen for a while. This is an interesting car because it has an original '63 FI block. The original numbers were intact as were the broach marks. Any NCRS judge would have deemed it original. Several years ago when I first saw the car, I told him what the block was and said it might be quite valuable to the current owner of that '63 FI Corvette if the car still existed.

I was aghast to see that the block had been decked - circular mill marks and all traces of the numbers were gone. He told me that a cylinder got scored and had to be sleeved, which required decking the block. He did say that he copied the numbers down, but that's probably not of much value. In any event, he was not interested in trying to get the block back to the original owner regardless of what it might have been worth, but it was a great "training tool" for an OE block since with no fenders, etc. the stamp pad was very easy to see in great detail without a flashlight or magnification, and I had used it several times to explain the nuances of an original unmolested block stamp pad to other interested persons.

If anything, a lot of restamps look "too good". Even if the font and size looks okay, the characters are usually lined up too well and the depth of penetration is too uniform. In production the worker loaded the gang stamp with the proper characters and whacked it with a hammer. Depending on gang and die wear the individual characters could be slightly tilted or off line and the depth of penetration has quite a bit of variation, particularly on the VIN derivative that was stamped by St. Louis. The Flint date/engine code stamp usually looks a little better and is a larger font.

If you attend some NCRS events, bythe time you look at two or three dozen original stamp pads you get a good qualitative understanding of what they should look like, and most restamps end up sticking out like a sore thumb.

Duke

 

I had the same issue a year ago. In hemmings, I found and I rented the correct holder and numbers from engines unlimited and I stamp it and it came out perfect.
Curt

 

I'm sure it will run better if the block is restamped. Check on e bay ...... Alot of NOS ( Numbers Of your choice Stamped ) being traded there daily.

 

A friend of mine had his 66 corvette recently judged after a body-off. The judges docked him on his engine pad because the broach marks were hard to see. It is the original engine. 40 years of engine rebuilds (hot tanks?) rust? wore away the broach marks. I don't know, I believe some of these judges see so many restamps on the judging field, they can't tell a real from a fake. IMHO

 

My opinion (FWIW).... follow what SWCDuke offers. My thought is that what he is saying addresses your issue correctly. But, just my view....

 

Pad has broach marks, machine shop that did the job uses a process that produces broach lines.

 

I always wondered that if anyone could find and piece together (or recreate) a linear Cincinnati Milling Machine Company machine, they could make a mint making "exact reproduction" broach marks. I heard these machines were about 100 feet long, however, so I guess the "start up costs" for such an enterprise would be too high.

 

most likely the wrong kind of broach marks though. As Duke explained, the factory marks are linear - straight, while broach marks created when the block is decked are circular.
This is pretty easy to see the difference and easy to tell a block has been decked and therefore restamped if you know what to look for.

you may fool someone who is not knowlegable on older Vettes but not someone who is more experienced and certainly not any decent NCRS judge if you plan on restamping to go thru judging

 

great, just what we need, another way for the clones and people creating clones to be better passed off as original. With the high $$$'s on these cars now, the last thing we need is another way for the "cheaters" out there to fake up more cars and pass them off as original to get the big bucks.

 

The stamps for the numbers and such are not a problem at all! This is of course with the right stamps! The problem is with the Broach Marks!

I don't know if this guy can do a perfect job, but maybe??

http://cgi.ebay.com/ebaymotors/ws/eB...category=34202

It is amazing how much Hemi clones go for, and Corvettes are all wrapped up in this numbers stuff!

There are Top Flight cars that are not real! Go Figure!

Can you imagine if GM found the build sheets for all Corvettes built before 1972!

 

Seems to be a lot of people offering "broaching" and restamping services.

I have noticed that they never post pictures of their work.

I wonder if their broach marks really do look original or maybe only approximate original?

One thing's for sure, they may be shy about showing their work but they're not very shy about their prices.

 

I believe I read on the NCRS discussion board something on this topic.
From what I remember, you are better off leaving the pad blank, than trying to restamp it and getting caught by an NCRS judge. I think there is only minimal point deduction for a blank pad, but a more severe deduction for a restamp. Since it is the original motor, everything else should match. The idea is to discourage forgery.

 

The pad carries 88 points in NCRS judging - 25 for the engine plant stamp, 25 for the assembly plant VIN derivative stamp, and 38 for the pad appearance and surface (broach marks). Re-stamp or blank (decked) pad both carry the same deduction - 88 points (out of 4500 for the whole car, and you can lose up to 270 points and still Top Flight the car). 88 points is about the same deduction you'd get if the lighter didn't "pop", the clock was quartz, and the windshield washers didn't work.

 

I believe the broach marks were created by a process called shaping an older process using a lathe tool and a horizontal motion for the metal removal process. This signature can be easily replicated with many tools today. And why, if an engine is original, but had to be sleeved and decked should the owner be penalized.
CharlieF
66 Coupe

 

Was the machine actually a broach or more accurately a slab mill?
I picture most broaches as a hole forming operation (I.E. a keyway cutting process).
Linear tool marks are normally produced by a slab mill, a shaper or a planer.
Anybody got a picture?

 

Yup, just happen to have one. This is the horizontal "block broach" (also called a "slab mill") machine in the block line. Two broach cutters are shown - the one on the left broaches the pan rail and the upper half of the main bearing bores, then the block is flipped over, registered and clamped on the pan rail, and the one on the right broaches the deck surfaces and the top horizontal surface between the decks. Each lateral row of cutting blades in each broach is set about .001" deeper than the row ahead of it; the block is clamped solid on its pallet, and the overhead broach has about a six-foot stroke longitudinally across the block surface; one pass for the pan rail and one pass for the decks and top, and it's done. Fresh blades in the tool left hardly any broach marks at all; as the blades wore, the broach marks became more visible.


(Terry McManmon photo)

 

I'll have to cross that one off my Christmas list, looks a bit on the large side.

JohnZ has pictures of everything automotive.

 

JohnZ...The answer man

 

If John doesn't know - nobody does