CRG Discussion Forum
Camaro Research Group Discussion => Decoding/Numbers => Topic started by: 1968z28 on December 08, 2014, 08:00:18 PM
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is there a way for a rookie to verify a genuine 302 pad stamp? how do you know if it's real? is it the letter size, style, or what? what sizes are the engine code and vin? do you just measure the letter height?
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To answer the 1st question (which largely will answer the other ?'s): In a word - NO. That is why there are terms like rookie, newbie...etc, because average Joes cannot tell. And that is good, why? If everyone knew, then there would not be "rookies", everyone would be a Pro and everyone would know what to do to perfect the fake world we live in. So, leave it to the Pros on here and post a pic and they will give an honest evaluation to help avoid the fake trap.
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Can't speak for '68s but '69 DZ block stamps had several subtle changes over the 14 month production run. That means there are overlapping dates for August, September, October. And guess what? A DZ block stamped in '68 won't necessarily match the same date in '69. DZ engines weren't built every day and there are 3 block casting numbers to deal with. Tonawanda blocks are not identical to Flint even for the same casting number. For the most part all blocks built on the same day have the same stamp.
We are amassing a library of stampings for comparative purposes. Anyone that wants to help out, send a clear photo of your block stamp to Kurt or myself.
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i'm anxious to see the MO examples. could someone include a scale next to both size letters so i can at least see the right size? also what letter spacing? did they use the same size stamps on muncie transmissions?
if a 68DZ used different stamps than 69DZs, sounds like there was more than 1 set of stamps used. is that only true for DZs or any engine during that period?
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is there a way for a rookie to verify a genuine 302 pad stamp? how do you know if it's real? is it the letter size, style, or what? what sizes are the engine code and vin? do you just measure the letter height?
If you want to know if it's real, post a picture...Joe
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i don't have a picture. i'm trying to buy one and don't want to get burned. is this some secret code or something? seems there could be a few clues explained?
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My $0.02
Main reason is because the fakers or restampers of the world are getting better and better by the day. This is the main reason for the "secrecy". Unfortunately or fortunately it takes time and experience researching to get to the point that several here have achieved. This is a passion and a hobby. ;)
I just wanted to add that you do not want to rush into a purchase. You will need to research every car you look at to make sure you are getting what you want. It will be somewhat of a long process especially for the novice.
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i don't have a picture. i'm trying to buy one and don't want to get burned. is this some secret code or something? seems there could be a few clues explained?
Post a pic. I've got a known original MO stamped block to compare it to, plus a good rule of thumb is to look at the block deck surface - milling feed lines from decking or surfacing that run at a tangent to the stamping are usually a dead giveaway that it's probably restamped. Too clean a surface is also an obvious. After that, font size and character shapes are clues that "sumting wong" -
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The fonts of MO stamped engines did not remain the same through the 1968 model year. Like DZ stamps in 1969, there were subtle changes.
If you find a car you are interested in buying, get a picture of the engine stamp and post it here if you want to know if it is genuine or not.
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it looks like the date code is made with gang stamp and vin was stamped individually because they're out of line. is that right?
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That's starting to look good. Now DO NOT use a screwdriver or any chisel type tool to finish cleaning the pad area. Not even a hard bristle brush.Use carb cleaner or brakleen and a rag and get the rest of the paint off. ALL od the paint. Then take close-up pictures, as close as you can get that are CLEAR, showing the actual original broaching of the block surface. Like my stamp below. And soon you will have your answer... Danny
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I totally agree with Danny; what we can see doesn't look bad, but too much paint and not sufficient resolution/detail to ascertain...
If I see factory broach marks, and the stamping is good and consistent with factory marks, then there would not be anything in the stamping to raise issue (but I still want to know *everything* I can find out about the block.. it's cast date, cast no, the heads and other parts on it, if it's running does it 'run correctly' per the app code, etc).. before I'd make a 'buying determination'...
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Can you post the VIN please?
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1968z28, First and foremost welcome to CRG :) You come to the perfect place for answers.
I (Very new here also) gotta agree with all the others here. We are HOBBYIST here and without sounding harsh and taking this the wrong way I think you'll understand and appreciate why your not exactly going to get pics showing any measurements of font style and spacing.
1) There were several font styles used and they could vary day-to-day... ex "I" was used as "1" in some setups. CRG has a large data bank of REAL VIN stamps and dates to compare any pics you can get. If it was stamped on the same day and location then it'll look the same as one in the data bank.
2) If we (The hobbyist) posted pics showing measurement, then we'd be shooting ourselves in the foot. We'd be teaching/showing those who want to do nothing but merely profit from new guys like you/me by selling a fake Re-stamp. And that's not what we wanna do. Heck there are guys out there that would stamp their mothers backside if they thought they could sell her off as "Rare one of a kind" ;D
On my journey I searched high and low.. I even bored these guys ;D for several months on end with Trim tags and engine stamps. I got my answers right away. What I'm saying is.. be patient if your looking for something in particular. Post as many pics and as close up as possible. Some of these guys here can tell in a split second just looking for broach marks, decking, an old stamp or fresh looking stamp made to look old, they've seen it all.
and last.. if someone gets offended because you want to take a pic and have it checked out... then run and run fast !
Good luck, and welcome again
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it looks like the date code is made with gang stamp and vin was stamped individually because they're out of line. is that right?
Correct. VIN and engine code are stamped separately. Note the positioning and fonts in the following pic -
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Note VIN and engine code line mismatch -
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Not a great pic, but I don't like it.
What's the VIN?
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I'm a little surprised -
I helped buy this block for a friend nearly 20 years ago. It's not a match to my '68 Z, but very close in date. I built the long block myself, plus sourced every part going into it.
Block was standard bore when I bought it, deck had never been touched up or resurfaced in any way prior to going to the machine shop. Block was bored .030, fitted with 1st design factory TRW ('67 thin rings)pistons purchased from the same guy, who also included the manifold and original distributor. .010/.010 original 1178 crank, pink pressed rods. If you're concerned with the pad surface around the stamp, it looks like it was scraped - no milling feed lines on the rest of the surface. Surface is completely flat, no signs of tampering or filling. My thought has always been not to try and pass this off as my original; it's someone else's block, but it's an MO, rebuilt with GM original parts.
I asked if this car's VIN was in the database sometime back - the response was negative. If the car should show up, I would gladly entertain a transfer to the owner (otherwise it will power my '68 for the rest of my life/ownership).
http://www.camaros.org/forum/index.php?topic=12082.msg99143#msg99143
Regards -
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People can have differing opinions on such matters.
Although insufficient information/imagery was included to be anything close to 'absolute', I didn't see anything in the presented data that would cause *me* to think it was not an original block and stamping. Just my opinion.
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it looks like the date code is made with gang stamp and vin was stamped individually because they're out of line. is that right?
Is this from the car you are interested in? The image of the V0417MO stamp.
If so, can you have them clean off the paint on the pad with some lacquer thinner and a rag? Then take a better picture.
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Steve,
Sorry, I was looking at the V0417MO pad when I said that!
The V0604MO pad is fine.
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Steve,
Sorry, I was looking at the V0417MO pad when I said that!
The V0604MO pad is fine.
Kurt,
Thanks for clarifying - I started to question my eyesight.
Regards,
Steve
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how were the decks surfaced on these blocks? someone said they should have broach marks. is that right? how does a broach work compared to today's techniques?
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how were the decks surfaced on these blocks? someone said they should have broach marks. is that right? how does a broach work compared to today's techniques?
Here's a wiki article for an understanding of the broaching machine and how it works:
http://en.wikipedia.org/wiki/Broaching_(metalworking)
The type of broaching machine used for the blocks was a linear broach, which machined the block deck in a single pass (from front or rear or rear to front) which leaves fine machining lines running longitudinally (from rear to front) on the deck surface. Contrast that to the rotary cut marks made by the typical milling machine (rotary) used in machine shops. When you inspect the front stamp pad (very closely), preferable with some amplification, on an original deck surface you should see fine parallel lines running from under the head and coming straight forward (no angle, no rotary marks). When a machine shop 'decks' a block, rotary cut marks will be left removing the original broaching marks, and which may or may not (depending on the depth of the cut) remove the original stampings also. We have some folks on this forum who actually worked for GM or for the Flint or Tonawonda engine plants that hopefully will elaborate (or correct) what I've said here... :)
Beware: There are rumors of stories of people who totally remove the original stampings and broach marks, and 'simulate' the original broach marks for a new (non original) stamping for profit or misrepresentation. A 'clean fresh new-looking' deck surface would make me suspicious of this.
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For the big answer you can google broach marks. The short answer is an engine plant doing thousands of blocks a day had MASSIVE milling-grinding machines. leaving specific marks that your local machine shop can not duplicate with their little machines. Re-stampers try and duplicate but the experts can still tell the difference. I just cannot tell you how they would know the difference.
Rick
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The Flint and Tonawanda block broaches were about the size of a locomotive, and machined 5,500 blocks per day in two linear passes - first pass did the pan rail and upper half of the main bearing bores, and the second pass did the block deck and front and rear "wall" surfaces. See photo below showing both sets of broach blades.
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Awesome picture John. Thanks for posting it!!!
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yes thanks john, that picture clears it up for me.
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Beware: There are rumors of stories of people who totally remove the original stampings and broach marks, and 'simulate' the original broach marks for a new (non original) stamping for profit or misrepresentation. A 'clean fresh new-looking' deck surface would make me suspicious of this.
Here's something scary !! Check these guys out. Re-stamp and re-broach your block and claim that it's good enough to pass judging NCRS Bloomington Gold Duntev Award. Isn't that something ? I also remember hearing someone a few years ago (Can't remember where I heard it) tell me they can broach your block by using a T-square and dragging a file across it. Talk about taking someone for a ride !
http://engineslimited.com/cms/index.php