I recently purchased a 1987 IROC-Z and I am trying to determine what engine I have in the car.

The car was manufactured as a 305 TPI car. This I have determined by the VIN #, Emission Tag under the hood and Accessory info tag under the console storage door, no 5.7 emblems anywhere.

I know the previous owner who only had the car a short period of time. All the info he has came from the original owner. He was told that the engine was replaced with a 350.

I realize that the block has numbers cast or imprinted on it but would they be definitive enough for me to tell what it may be?

Thanks in advance for any assistance.

 

there will be a cast one the side of the block about 6 inches from where the bell housing bolts in it will say either gm 5.0 or gm 5.7