how to ID sbc displacement

[gravdigr]

I'm looking at a blazer to buy and the seller doesn't know the engine displacement just that it's a V8. Is there any way to tell externally from the engine? It's in an 86 blazer.

 

[big83chevy4x4]

if its stock then is most likely a 305.

under the alternator is the stamping codes. the last 2 or 3 letters tells you what it is and what year. take those letters and match them up here

 

[Muddytazz]

Mortec's webpage

 

[wayne]

Also look on the radiator support for the sticker.