Casting Question

Where would i find my engine casting on my car. Its an 87 Iroc, but i know the engine was swapped. Its a 350 TPI.

Does anyone know?

on the back of the block on the "lip" above the crank on the drivers side there should be some numbers. If they are the original heads for that motor, not the car, then inbetween the push rods and the springs there are some numbers. And if you have the motor pulled apart, again if original to the motor, there are numbers on the crank on one of the balancers.