How can you tell if a car has it's original motor - or "matching numbers?"
Thanks!, Rich

 

What year and model of car are you talking about?

 

You could compare the numbers stamped into the motor to those found on the VIN or protecto-plate.

As mentioned, it depends a lot on the year of the vehicle, as the practices varied. The main dividing line would be 1967 vs 1968... 1968+ the engine BLOCK and the trans case had to have the VIN derivative "stamped" in - not a cast-in identifier which is commonly [and erroneously] referred to as a "stamping."

 

1968 and later:



- Eric

 

pre 68 must have protecto plate which will show engine number located on passenger side head pad usually just behind alternator. Again this would only prove that specific head is numbers matching to your car and the other head along with motor may have been replaced. Then you must check jullian dates on block and head(s). Much easier to prove a 68 and up Olds to be numbers matching, as no paperwork or protecto plate is needed.

 

Mine is a '77 Cutlass 350. I found the numbers 557752-3B on the top of the front of the block facing the radiator & just behind the water pump. The VIN # for the car is: 3M57R7M315078. Obviously these numbers don't match up. Are there other numbers on the motor somewhere else? I've seen cars advertised as "numbers matching" -- am I missing something? Thanks! Rich.

 

Hi Rich
That's the casting number between the water pump and intake manifold. The vin will be stamped into the block on the driver side. There's a pad that may be hard to see behind the alternator and power steering brackets. Attached is a thread where I took photos of various engines, including one from a 1977 Cutlass. I've also got photos of the vin number stamped on transmissions if you want to check that too. Let us know if you have any additional questions. John

P.S. this is the same location as Eric's diagram... but sometimes a photo with all the clutter in the way helps located it!

https://classicoldsmobile.com/forums...s-engines.html

 

John, you don't know how many times I've used your pics to help others. Thanks for doing that.

 

The only thing I saw was the alphanumeric "3A." Is that what I'm looking for? Otherwise I'll probably have to move the alternator out of the way to see anything else (?), Thanks, Rich.

 

I posted a picture from the Chassis Service Manual that shows you exactly where to look,



You didn't even acknowledge its being there, but instead described the casting number and posted
Then John posted a link to his excellent photos, which included him pointing to the number on two different cars



P1010401-1.jpg

I'm not sure how much more we can do for you here. Just look at the place on your engine block that we have taken the time to show you.

And, yes, you may have to clean the area, remove the alternator brackets, or use a mirror.

- Eric

 

After I moved the alternator out of the way I was able to see it, Thanks guys!

Rich

 

OK, so, did you find "37M315078" stamped there, proving that it's the original block?

 

Yes I did, thanks for all the awesome help!

Rich