What would this 1M stamp mean on my engine block?

 

What engine option is the car.

 

427/400...l68.

 

IM is 66 thru 68 427 390 or 400 hp corvette. I was commonly used for 1 and visa versa. they didn't care how pretty the stamp was. they didn't give a little bit of a crap if somebody 50 years in the future is gonna have an issue with an ugly factory overstamp. all they cared about is the correct stamp on the block. that being said, it could well be somebody later doing this also.

 

More pics/info...tri



m tag, Vin and copy of build sheet.

 

IM is for a 68 L36. Your car is a 69. It should be an LQ for 400 hp cars with standard ignition and MK if you car has transistorized ignition.

 

Here is your car:https://www.c3registry.com/index.php...iLviMWsfayBQ==

 

According to your Trim tag the build date is September 21 1968. Your engine stamp is Jan 11th which would be incorrect for the car. Here is an original engine stamp for an original L68 standard ignition car to compare to your. Now, your car is early and does have TI according to the tank sticker which was unusual and there could be a case for a factory grind out. But I am not seeing that with your stamp. What is the castling date of your block? Also, can you post a clean version of your tank sticker?

 

I hope you didn’t write over your ORIGINAL build sheet?

it is very difficult to determine if an engine pad is original in most cases from pictures on the Internet but MANY people that are far from experts don’t seem to be able to help themselves from telling owners that theirs is a restamp. It is a pet peeve of mine. If the validity of your engine pad is important to you should really have a true expert look at it in person. The problem that many people will find from looking at your pictures are it is hard to see the factory broach marks on the rest of the pad. Some times they can be removed, filled in or obscured by scrapping or sanding the pad to clean it. They often are missing on part of the block IF when the factory restamped it did what is referred to as a grind out where they grind out the old characters they want to change. From what I see from your in your picture it appears that they simply stamped over the underlying characters. If and when you decide to sell it people will question this so it will be worth your while to have an expert to verify it.

 

69 Hemi would agree with you, If you want to hire an expert to tell you reach out to Al: http://www.ccas4vettes.com/pr01.htm

That being said, the broach marks appear to me machined and the date in the engine stamp is nowhere close to the build date of the car. Also, the suffix code MK for an L68 w TI wasn't used until early 1969. So if you ordered an L36 with TI early in the year the engine plant stamped the standard LQ suffix code and used the standard distributor. Once the engine got to the St Louis plant they replaced it with a TI distributor. This was the process for early L36 cars with TI until they came up with the MK suffix code at which point the engine plant installed the TI distributor before shipping. All early L36 engine stamps I have seen have been LQ. The only "I" suffix codes I have seen carry over form 68 to 69 is the "IT" stamp for the L88 engine.

 

Wow....lots of good information, but still confused as to what I really have. So, here goes with the story on how I got the car and info. No, I did not write over the original build sheet and in fact, I do not even have the original build sheet. That is a copy that was provided to me from a previous owner and the original was lost sometime along the way. Based on responses, I question whether this build sheet is even for this car??? So here goes....

I bought the car from a local to me guy who bought the car from Gregg Popovich (coach of the San Antonio Spurs). The guy never titled the car in his name, so I received the car with Popovich's name still on the title. I have since put the title in my name. I started doing research and reached out to the outfit in Wisconsin that sold the car to Pop....I wanted to verify the story. The owner confirmed that a group of players from the Spurs bought the car for Popovich, as a gift back in 2009/10. The guy in Wisconsin gave me some history on the car and provided me the copy of the build sheet, which is what I posted. This build sheet got lost somewhere in the transaction to Pop and my local guy. It was all communicated as "matching numbers" and I see common numbers on the VIN and Engine stamp, but I never knew what the extra 1M stamp represented. I always just figured there was some sort of work done on the engine, but figured it was the original block since other numbers "matched".

That's all the story I got and kind of disappointed to now see that things don't necessarily "match". Maybe I will try to find a local expert to help, but that's why I was posting on here....

Title is written as a 1969 and nothing funny about the title or anything being rebuilt.

 

You can reach out to Al at the link I gave you. He may have examples of IM being used for early L36 TI cars. I have a database of engine stampings and I don't have another early L68 car with an IM stamp. Not saying it never happened, but I have other early L68's that have the lQ suffix code. The Tonawanda engine plant stamped these engines in batches, so there tends to be consistency in the stampings. If a car has an engine stamp that is an anomaly, like yours does, it helps to have the protecto plate to authenticate how the car left the factory. On some cars for example 435 HP automatic cars in 69, there have been factory grind outs. I am curious to know what the casting number and casting date is on your engine block. Also, does your car have the TI module in the front drivers side fender and other tell tale signs like a single fuel line consistent with L68 cars?

 

Thank you DKM...you sound pretty knowledgeable and certainly beyond my knowledge or ability. I will call the number via the link you provided as I am now very curious.

 

mraynek sent you a PM.

 

Can anyone tell from the OPs pictures what the characters are that are stamped over, I can’t.

 

I can't figure out the original letters either...I even tried looking at 68 engine codes. Nothing makes sense....

 

DKM.....I didn't get a PM, unless it's taking a while to come thru?

 

Just sent it again

 

It sure appears to me that the block has been restamped.

1969 Corvette VIN 02332 was built approximately Sept. 24, 1968, according to the C3 Birthday Calculator. The assembly date stamped on the block, 0111, is Jan. 11, 1969. It is impossible for an engine assembled in Jan. 69, to have been installed in a car built 4 months earlier. "IM" was the suffix code for the Corvette 427/390 in 66-67, and the 68 427/400, but in 1969, "IM" was the suffix code for a 350 2bbl in a Chevrolet passenger car (Chevelle, Impala, etc), not a Corvette big block. As DKM-106 pointed out, your trim tag has a body build date of Sept 21 (B21), which fits perfectly with the car's assembly date of approximately Sept 24, but not with the engine's January assembly date.

On the rear of the block, you will find a flange that the trans bellhousing bolts too. Cast into the top of the flange on the left (driver's side) will be a block casting number, usually a 7 digit number starting with 3. There should also be a block casting date on the block, either on the top right side of the flange, or possibly on the right side of the block itself, near the freeze plug (dates cast into the side of the block are near impossible to see from above). Knowing the casting number and date, could be helpful in identifying the block.

The suffix code may be a factory grind out, but the suffix code and assembly date now on the block, don't match the 427/400 engine in the car, or the car's assembly date, according to the VIN.

 

C3 Registry
First 68 was built September 1 1967
Last 68 was built August 19 1969

First 69 was built September 2 1968
This car was built September 21, 1968

The engine in question is a January engine (assuming casting month is Dec/Jan) regardless of what the engine codes and/or VIN numbers say. No way a January engine ever made it into a 69 Vette built on September 21, 1968, for that to have happened this engine would have had to been setting against the wall on the production line for eight months waiting on a car. That just never happened.

Nice car enjoy it for what it is.