Author Topic: Why Are Some Blocks Stamped and Some Not  (Read 2855 times)

TooManyReels

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Why Are Some Blocks Stamped and Some Not
« on: May 14, 2013, 02:33:10 AM »
Over the past few years, I have been watching and reading about original 69 Z/28 blocks with just the pad stamped, and some with the pad stamped and partial vin. # stamped by the oil filter. I understand from this site, why they changed the location of the partial vin. # and about when, so here is my questions.

With all the factory controls in place, along with a QC system they had back then, why weren't all car/blocks confirmed to be properly stamped both on the block pad and by the oil filter after they made the change?  Did it become so difficult to do during the production process to get done right, or did they just say oh what the heck, its not going to matter anyway and just let it go. Or, did they get it right and they are just that many re-stamp block out there these days.

As a hobbyist this continue to confuses me. Are there really that many re-stamps blocks out there these days and if so, about when did all the fakes start showing up.

Eddie
Eddie
63 Chevy II SS 570hp 560tq.
69 Z28 X33 Cross Ram JL8

69Z28-RS

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #1 on: May 14, 2013, 02:43:40 AM »
I saw poorly restamped DZ blocks in the '70's...  always very obvious...
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
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z28z11

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #2 on: May 16, 2013, 01:10:57 AM »
Take a look at these 2 - current advertisements. Some variations, all from the same vendor. No VIN stamp views offered on any of the 4 blocks that were on line. Top shot looks too fresh, bottom appears better, but still not 100% sure of it -

Judge for yourselves -

Regards,
Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06

69Z28-RS

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #3 on: May 16, 2013, 04:09:11 AM »
Over the past few years, I have been watching and reading about original 69 Z/28 blocks with just the pad stamped, and some with the pad stamped and partial vin. # stamped by the oil filter. I understand from this site, why they changed the location of the partial vin. # and about when, so here is my questions.

With all the factory controls in place, along with a QC system they had back then, why weren't all car/blocks confirmed to be properly stamped both on the block pad and by the oil filter after they made the change?  Did it become so difficult to do during the production process to get done right, or did they just say oh what the heck, its not going to matter anyway and just let it go. Or, did they get it right and they are just that many re-stamp block out there these days.

As a hobbyist this continue to confuses me. Are there really that many re-stamps blocks out there these days and if so, about when did all the fakes start showing up.

Eddie

1) I believe there was a federal law in place that required the major components (engine/trans) be stamped with the VIN.    I believe taht the factory complied in all cases.
2) I also KNOW that the stamped code on the rough cast surface near the oil filter ARE extremely difficult to read.
3) I suspect that the 'block restamper/fakers' try to take advantage of the difficulty of reading the block stamp on the cast surface
4) YEss, there are a lot of restamped blocks.  (I do not believe the two posted by Steve are original stamps...)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

TooManyReels

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #4 on: May 17, 2013, 02:37:21 AM »
So would this mean, that all blocks would have been stamped at the factor by the oil filter.  Then could only assume that with no visible stamp by the oil filter means its not an original productions motor. A duck is a duck if its a real duck.

Eddie
Eddie
63 Chevy II SS 570hp 560tq.
69 Z28 X33 Cross Ram JL8

vtfb68

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #5 on: May 17, 2013, 03:24:18 AM »
Low performance engine blocks lack Vin # numbers in most cases.
   VT
05C LA RS/SS U2 712 L34 M21 BR
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"In the pursuit of accuracy"

KurtS

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #6 on: May 18, 2013, 05:15:47 AM »
I assume it was just the difficulty in stamping the VIN or the fact it was hard to confirm.
But most blocks are stamped - I've seen few that aren't. Most are hard to see.
Kurt S
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william

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #7 on: May 18, 2013, 02:14:47 PM »
To draw a conclusion that is statistically significant one needs at minimum an evenly distributed 5% of the total population. So for the '69 Z/28 at Norwood you would have to examine about 800 DZ engines manufactured from August 1968-October 1969.

sixt9x33rs

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #8 on: June 19, 2013, 08:34:39 PM »
Low performance engine blocks lack Vin # numbers in most cases.
   VT
The 69 L65 Convertible I once owned had the VIN clearly stamped by the oil filter. The engine assembly was late April. You may be referring to six cylinders?
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little_hoss

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #9 on: June 23, 2013, 04:00:17 PM »
Over the past few years, I have been watching and reading about original 69 Z/28 blocks with just the pad stamped, and some with the pad stamped and partial vin. # stamped by the oil filter. I understand from this site, why they changed the location of the partial vin. # and about when, so here is my questions.

With all the factory controls in place, along with a QC system they had back then, why weren't all car/blocks confirmed to be properly stamped both on the block pad and by the oil filter after they made the change?  Did it become so difficult to do during the production process to get done right, or did they just say oh what the heck, its not going to matter anyway and just let it go. Or, did they get it right and they are just that many re-stamp block out there these days.

As a hobbyist this continue to confuses me. Are there really that many re-stamps blocks out there these days and if so, about when did all the fakes start showing up.

Eddie

1) I believe there was a federal law in place that required the major components (engine/trans) be stamped with the VIN.    I believe taht the factory complied in all cases.
2) I also KNOW that the stamped code on the rough cast surface near the oil filter ARE extremely difficult to read.
3) I suspect that the 'block restamper/fakers' try to take advantage of the difficulty of reading the block stamp on the cast surface
4) YEss, there are a lot of restamped blocks.  (I do not believe the two posted by Steve are original stamps...)
Just wondering what would lead you to believe that the 2 posted block codes appear to be re-stamps? The first looks like it has the correct straight line broach marks but not real sure on the second one though. In reference to Chevrolet not stamping low performance blocks, my base model 307 3spd manual 1969 has the VIN stamped by the filter. Took awhile to see it, but once I cleaned the area it was pretty visible.
Eric

1967 Base
1969 Base 307 3spd matching #'s
1968 C-10 Short Fleet Custom

69Z28-RS

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Re: Why Are Some Blocks Stamped and Some Not
« Reply #10 on: June 24, 2013, 04:10:35 PM »
I suppose a better way to have said what I was trying to say, is that based on some of the characters of the stamped code being 'different' than those same characters in my own stamping, I was skeptical.   In particular, I didn't like the bottom of the 'Z'.   There was also a difference in the D and the 2 in those stamps.   that said, my opinion does NOT mean they are absolutely wrong, it just means I'd have to see a lot more evidence for those blocks and the cars they were in to be 'sure' that they were original stamps.   Maybe Flint engine had a variety of stamps/fonts that I'm unfamiliar with??   Maybe some others who have photographs of many 'known' good stamps can shed better light on those?   What it boils down to is that anything that 'appears' out of the norm of our experiences are met with initial skepticism.    I experienced a few examples of that this weekend at the Nationals, where I was initially skeptical, but on more complete examination of all the associated date, I changed my mind..  :)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan