Im about to purchace a 91 Z28. The guy selling the car says it's a 350 but I don't think he's very car savvy. where on the engine do I look to Id it, and what should I see?
Thanks

 

The engine block casting number is the only sure way, and it isn't easy to see - behind the driver side head on the bell housing casting.

Sometimes the last three digits of the casting number is cast into the side of the block, viewable from underneath. Get it up into the air (safely), have a light available, and look for it.

The 8th character of the VIN will tell what engine the factory put in it. "F" = 305, "8" = 350. But, even if it had a 350 in it from the factory, it may have been replaced with a 305 in the last 19 years.

 

Also, if it was built with a 350, it should have dual cats under it. If not, then the car is worth a few $$ less. Not all 350s actually came with rear discs in '91, in fact, most didn't. But the '91 350s should have a 3.23:1 posi. If it's a 5-speed, it wasn't a 350. GM did NOT offer them that way.