How can I tell the difference between a 5.0 and 5.7 tpi motor ?

 

block casting of suffix number or off injector size

 

could also be on the opposite side of the block depending on the age of engine

 

do you know what the numbers are or where I could find them ?

 

Just write down the numbers and type them into Google. There are various sites out there that you should be able to find that will tell you.

 

Put the block casting # up here and someone will tell you.

Late model blocks have GM 5.0L or GM 5.7L cast on the place shown above ; block casting # is on opposite side

 

Well, the reason im asking is because I'm looking to purchase a 350 and i want to know what the numbers should be when I go look at it.

 

It won't be exactly like that. Unless the block has the obvious 5.7L cast into it, you'll just have to run the numbers that you find on it. The factory has used many, many different casting numbers and codes for virtually the same engines. There's usually a code in front of the passenger's side head stamped into the ledge there. This is a manufacturing date code and a model identifier that would indicate what model, assembly plant and date.

http://www.nastyz28.com/sbchevy/sblock.php

EDIT: Be careful with this, engine codes were reused and aren't always listed. You have to look at the partial VIN and date codes to be sure of what you are getting. For example, my old truck has an engine code suffix of CLD. People could easily be fooled into thinking this was a corvette L-82 350 if they aren't careful. In reality, it's a TBI L-03 305 from a 91 camaro or firebird. A little bit more than a slight difference. The partial VIN gives it away.