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Hey all. What is the consensus, Is the entire stamping a restamp? The suffix only? The vin number? Or has the 1M been simply added after part of the suffix letters were removed?
Was able to make out the casting block number.....3916321. Was not able to find the date code yet, but will get the car up on my lift later today to try and pull more numbers. That casting code number appears to be consistent with a 68 block.
1968 Corvette Casting Numbers
Application Block Cylinder Head Intake Exhaust (left) Exhaust (right)
327 - 300 HP (early) Base 3914660 3917291 3919803 3872765 3872778
327 - 300 HP (late) Base 3914678 3917292 3919803 3872765 3872778
327 - 350 HP L79 3914678 3917292 3919803 3872765 3872778 427 - 390 HP (early) L36 3916321 3917215 3919849 3880827 3880828 427 - 400 HP (early) L68 3916321 3917215 3919850 3880827 3880828 427 - 430 HP (early) L88 3916321 3919842 3885069 3880827 3880828 427 - 435 HP (early) L71/L89 3916321 3919840 3919852 3880827 3880828
427 - 390 HP (late) L36 3935439 3917215 3919849 3880827 3880828
427 - 400 HP (late) L68 3935439 3917215 3937795 3880827 3880828
427 - 430 HP (late) L88 3935439 3919842 3933198 3880827 3880828
427 - 435 HP (late) L71/L89 3935439 3919840 3937797 3880827 3880828
Gets even better. The intake number is 3937795, which according to the chart above is belongs to a late L68 build. So, the comment in the C3 registry that says the engine has been rebuilt looks true? An early 68 block with a late 68 intake. Still working on pulling more numbers.
So you have an early 68 block. The casting date will be on the passenger side block by the freeze plug and the starter, it will be interesting to see what it is. They used the 321 block until Jan/Feb 68 so that this block is way too early for the car. Now I have seen unusual situations where an engine will go back to rework and then get sent out at a later date and go into a car with a long date discrepancy. But I haven't seen an early 68 engine in an early 69 build car other than the IT code L88 motors. If you go with the idea that the engine went to rework and shipped out later, the block would have been ground out and stamped with an LQ as there are earlier cars with the LQ suffix code stamping. Looking at your transmission stamping will be a good reference point. It you add the copy of the tank sticker, the big block hood in primer from the pictures on the c3 registry, I would be checking on items such as a single fuel line, redline tach, presence of a TI module, presence of big block rear end etc to verify you have the correct components that line up to having a 400 hp car.
I have personally owned / looked at a few C2 & C3 cars that were known original numbers matching cars and ALL of the casting dates preceded the car build date by roughly 1-3 weeks. Most if not all of these parts were still warn from the foundry when they arrived on the assembly line.
It is common for engine components etc to be fairly close to the build date of the car, but I have seen longer dates up to 6 months or so on items such as F41 shocks. For example the Delco shock plant punched out batches of F41 shocks and then St Louis used them as an F41 car was to be built. With low production numbers some of these parts sat until they were to be allocated to the job. That is what NCRS allows for a larger window.
I have personally owned / looked at a few C2 & C3 cars that were known original numbers matching cars and ALL of the casting dates preceded the car build date by roughly 1-3 weeks. Most if not all of these parts were still warn from the foundry when they arrived on the assembly line.
Good to know, I would of thought it to be a wider gap..... my 69 L36 car has a Dec 4th of 68 build date, here is rear diff stamping......sorry no hijack to the OP thread
Last edited by F2 Speedy; Dec 23, 2021 at 01:40 PM.
Whoever stamped the vin number actually did a great job. While there is always a bit of variation, but the stamp looks very typical compared to my collection of vin stamp pics. The fonts are 100% correct. It surprises me that the person stamping it did such a good job on the vin but such bad research on what a proper date and engine code should be there. But it’s clearly not possible to be the original engine.
DKM, the closest BB stamp I have to that vin is 702275. It’s a 390 but the vin looks much like the op’s stamp.
Also, you mentioned they used the 321 block up until Dec 68, I think you meant Dec 67.
Sorry, Ed good catch, I meant January 68. I believe there have been some February and March 68 build cars that has been observed to have the 321 block. The 321 blocks and the 439 blocks were used intermixed for a short time around that time period until the 321 block was completely phased out.
So I enhanced the engine stamp picture posted and it matched to a few other IQ 68 engine stampings. So at least we know that the original suffix stamp on the block was factory. Now to do some digging on the grind out and restamping
Ok,
So here are my thoughts on the motor. I believe the block is original to the car and engine vin and transmission stamp match and match other examples of early 69's I have now that I have gone through them all. The IQ was a 390 HP automatic block and it is plausible that they made more automatic L36 engines for cars then people wanted so they had a batch of leftover motors. With this car being an L68 with TI, I believe it was a grind out in St Louis and the 1M was stamped there. All the options on the car align with the copy of the tank sticker. I would suggest having Al Grenning certify it to give you peace of mind.
DKM and Ed thanks for the education!!! Very interesting thread with excellent information.
The reason I posted my question was that the fonts and lettering looked good to my novice eye and I was wondering what everyone else saw other than the added IM stamp and the incorrect date that was so concerning. Excellent detective work!!!! Ike
What a fun day yesterday researching this with DKM. As more and more of the numbers and dates starting matching up, it made me feel good. I can't thank DKM enough for the time he spent with me all day as new numbers became available. He is a wealth of knowledge and pure joy to speak with. Thank you again and what a fun day of researching.
