"Mexican" engine

I have a Chevy 250 which had these tags stuck on the side of the block. It was supposedly from a '67 Nova. Was it rebuilt in Mexico? Would it have hardened exhaust valve seats?

 

What is the engine? What are the rest of the numbers on it?

Can you get a clear picture of the logo on the left side? yes, close up photography is difficult...

 

Chevy 250 6cyl. I looked up the casting numbers, that's where I got the 67 Nova info from.

 

If it has a 1967 car head on it, it won't have hardened seats, unless someone installed them...which you can tell by looking at the head (after removing it from the engine)

 

If it is running fine, don't worry about the hardened seats. Most street cruising the hardened seats aren't really needed. The worse case you have to pull the head and do a valve job a little sooner; and can install the hardened seats at that time.

 

I am used to putting in a shot of "phoney lead" (fuel conditioner) in the tank of any older unknown engine (which I have not had the head off), as I have found this works, at least I have never had to pull a head to rescue a bad exhaust valve. This motor (250) runs well, and as I was about to put some goop into the tank, I was just wondering if it already had hardened seats, as the unleaded fuel /hardened seats was introduced at different times in different countries, and the U.S. may have already had them back in '67. I will just ***ume it has hard seats as it has recently been rebuilt at some stage (by the amount of excess clean silicon that I had to get rid of to change the pan gasket, they used the stuff by the gallon, with no gaskets). What's with the "Mexico" tags? Was that a common thing in the U.S., to get engines rebuilt in Mexico? I have heard of Tijuana upholstery shops, but engines?

 

That's why I asked for better pictures of it, to see if we could figure it out. I've never seen anything like that.

But there were a lot of Chevy engines made in mexico, I think they still make them there for new trucks. I've seen "Hecho en Mexico" cast into blocks on most of the stock performance crate small blocks, and on the 292 replacement engines sold by CHevy in the 1990s.

 

Many reman companies still send to Mexico for rebuild. O'Reilly for one