He's asking about '69 and '70 blocks.
Restamp concern
Thread Starter
Instructor
Joined: May 2007
Posts: 112
Likes: 1
From: Chadds Ford PA
Restamp concern
I recently purchased a 1970 convertable, big block, 4 speed. It was suggested to me that my block may be a restamp based upon the difference between the block casting date of Aug 1969 and the car's production date of June 1970. There are also some pretty obvious grind marks under the right side of the serial number.
I understand that there was a delay in production that year and that 1970 cars were first made in January of 70 rather that September of 69. The block couldn't be for a 69 car because the 454 first came out in the 1970 models. Does anyone have any knowledge about the delayed production and when the blocks were first cast for the 1970 cars?
I'm also concerned about the grind marks. Every other number and production date on the car matches up. It doesn't look to me like there was an intent to decieve because the grind marks are very obvious. If someone wants to fake a block, you would think that they would do a much better job. Is there any way to find out if this happened at the factory?
I understand that there was a delay in production that year and that 1970 cars were first made in January of 70 rather that September of 69. The block couldn't be for a 69 car because the 454 first came out in the 1970 models. Does anyone have any knowledge about the delayed production and when the blocks were first cast for the 1970 cars?
I'm also concerned about the grind marks. Every other number and production date on the car matches up. It doesn't look to me like there was an intent to decieve because the grind marks are very obvious. If someone wants to fake a block, you would think that they would do a much better job. Is there any way to find out if this happened at the factory?
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Assembled engines were shipped to St. Louis on an average of two weeks (sometimes longer) before the car was assembled. As an example, the engine in my '68 was assembled on April 9, 1968. The time build code on the car is Saturday, April 20th. Eleven days. The block casting date is April 4th.
If '70 did not begin until the latter half of January, the first engines could have been assembled at the beginning of the month, then shipped to St. Louis. Casting dates could be very late December, 1969, or early January 1970.
Safety Car
Joined: Apr 2007
Posts: 3,849
Likes: 367
From: PHOENIX AZ. WHAT A MAN WON"T SPEND TO GIVE HIS ASS A RIDE
Block casting # should be 3963512. It was on the back of the block. I am sure that your block is a 427. the 1970 Vet /454 CI did not come out till FEb. 1970. Blocks were the same bore but thay were strocked.SORRY KEN 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Administrator
Joined: Jul 2000
Posts: 54,006
Likes: 6,215
From: About 1100 miles from where I call home.
I recently purchased a 1970 convertable, big block, 4 speed. It was suggested to me that my block may be a restamp based upon the difference between the block casting date of Aug 1969 and the car's production date of June 1970. There are also some pretty obvious grind marks under the right side of the serial number.
I understand that there was a delay in production that year and that 1970 cars were first made in January of 70 rather that September of 69. The block couldn't be for a 69 car because the 454 first came out in the 1970 models. Does anyone have any knowledge about the delayed production and when the blocks were first cast for the 1970 cars?
I'm also concerned about the grind marks. Every other number and production date on the car matches up. It doesn't look to me like there was an intent to decieve because the grind marks are very obvious. If someone wants to fake a block, you would think that they would do a much better job. Is there any way to find out if this happened at the factory?
I understand that there was a delay in production that year and that 1970 cars were first made in January of 70 rather that September of 69. The block couldn't be for a 69 car because the 454 first came out in the 1970 models. Does anyone have any knowledge about the delayed production and when the blocks were first cast for the 1970 cars?
I'm also concerned about the grind marks. Every other number and production date on the car matches up. It doesn't look to me like there was an intent to decieve because the grind marks are very obvious. If someone wants to fake a block, you would think that they would do a much better job. Is there any way to find out if this happened at the factory?
Administrator
Joined: Jul 2000
Posts: 54,006
Likes: 6,215
From: About 1100 miles from where I call home.
Post some pix of the engine pad. Engines were changed at St. Louis and blocks were restamped, but a time lag of August 69 to June 1970 isn't likely. That period is almost a year. Just the same, it cannot be discounted as a possibility.
Assembled engines were shipped to St. Louis on an average of two weeks (sometimes longer) before the car was assembled. As an example, the engine in my '68 was assembled on April 9, 1968. The time build code on the car is Saturday, April 20th. Eleven days. The block casting date is April 4th.
If '70 did not begin until the latter half of January, the first engines could have been assembled at the beginning of the month, then shipped to St. Louis. Casting dates could be very late December, 1969, or early January 1970.
Assembled engines were shipped to St. Louis on an average of two weeks (sometimes longer) before the car was assembled. As an example, the engine in my '68 was assembled on April 9, 1968. The time build code on the car is Saturday, April 20th. Eleven days. The block casting date is April 4th.
If '70 did not begin until the latter half of January, the first engines could have been assembled at the beginning of the month, then shipped to St. Louis. Casting dates could be very late December, 1969, or early January 1970.
Actually, typing while thinking is probably not best. I think the guidelines are about 10 days to about 8 weeks, making Mike's '68 just right as well as other cars I was thinking of that have an 8 week spread.
What's OK? 10 weeks? 12? What's too long a period?
Last edited by vettebuyer6369; May 4, 2007 at 06:50 PM. Reason: answered my own question
Melting Slicks
Joined: Nov 2004
Posts: 2,672
Likes: 6
From: Nevada City California
3963512 castings on blocks were used for both late '69 production 427's and '70 production for 454's. You would need to pull the oil pan and look to see if the cylinder bores have the reliefs to clear the crankshaft.
Thread Starter
Instructor
Joined: May 2007
Posts: 112
Likes: 1
From: Chadds Ford PA
Are there any other numbers inside the block, on the crank, rods, pistons, etc. that would help to authenticate the motor? The 4" stroke verifies that it's a 454. Are there any markings to match the crank to the block?
Thanks.
Melting Slicks
Joined: Sep 2006
Posts: 3,386
Likes: 2,607
From: Burning Jet-A
What about cast in Aug 1969, and then machined and assembled by June 9 1970? Its a Monday. A long time for a block to sit around, but they may have wanted to get rid of those 512's once and for all.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Blocks cast in Aug '69 could have sat around for 6-8 months with the 1970 GM strike. They would have been "in-plant" in August and the strike started in September. Plants were shut down at that point, and there was no production until March or April. It would have taken time to "ramp up" production, and [back then] there was no "first-in; first-out" stock inventory system. I believe it is quite possible that your engine is original to the car.
Burning Brakes
Joined: Jul 2002
Posts: 1,185
Likes: 2
From: Indianapolis IN
When was the period of the strike anyway? was is late 69 until the march or April 70 that you mention?
Was there another strike is late 1970? (No 71's were produced in the month of October 1970 - was this due to strike)?
Was there another strike is late 1970? (No 71's were produced in the month of October 1970 - was this due to strike)?
Drifting
Joined: Aug 2004
Posts: 1,354
Likes: 0
Blocks cast in Aug '69 could have sat around for 6-8 months with the 1970 GM strike. They would have been "in-plant" in August and the strike started in September. Plants were shut down at that point, and there was no production until March or April. It would have taken time to "ramp up" production, and [back then] there was no "first-in; first-out" stock inventory system. I believe it is quite possible that your engine is original to the car.
Pro
Joined: Mar 2006
Posts: 724
Likes: 1
From: NY
St. Jude Donor '06
I agree with those above as to the block sitting around for a year does sound suspect. Also, I hate to say this, but you have a very desireable car and people are faking them all the time. As with the 67 BB's, there are now more on the road than were ever produced. The grind marks would be a dead giveaway to me. That car is worth far more as a numbers matching then not. If you just got it then it looks like even with the grind marks they got away with it. There are more faked blocks out there because the money is what it's about now. Without seeing it, I would say it's a correct block for the car but not the original.
Racer
Joined: Dec 2005
Posts: 368
Likes: 4
From: . New Zealand
I agree that in this threads case, there is cause for concern that doubt of OEM exists for whatever reason, others may disagree but the time gap does not give confidence, unless others have date gap examples around the same time period for the particular engine model.
I'm thinking the numbers matching thing is likely to get out of hand, driven by commercial value. This leads one to think, that unless there is something done to prevent it, I'm picking, there will be a company, probably Asian, able to produce a "numbers matching" block or heads, with date codes to order and stampings no one could tell from the original without detailed forensic science. They could do this legally by gaining a licence to produce these as restoration parts, the same way that companies produce replacement classic car parts.
It would be scary If that happens, what credence will there be to any supposed no's matching cars?
As to the argument whether its against fraud law, the foundry could hide behind customer demand technocality.
Any agrieved parties would then be forced into a "prove that it isn't OEM" strategy for proof.
I'm thinking the numbers matching thing is likely to get out of hand, driven by commercial value. This leads one to think, that unless there is something done to prevent it, I'm picking, there will be a company, probably Asian, able to produce a "numbers matching" block or heads, with date codes to order and stampings no one could tell from the original without detailed forensic science. They could do this legally by gaining a licence to produce these as restoration parts, the same way that companies produce replacement classic car parts.
It would be scary If that happens, what credence will there be to any supposed no's matching cars?
As to the argument whether its against fraud law, the foundry could hide behind customer demand technocality.
Any agrieved parties would then be forced into a "prove that it isn't OEM" strategy for proof.
Last edited by Thmprr; May 8, 2007 at 08:33 PM.