305 Question about valves

[AZKen]

Is a 305 an interference motor or not? In other words, if timing chain or gear breaks/stretches will valves hit piston or is there clearance? Some Chevy motors are interference motors and some are not. Don't know if GMC 305 V6 is or not? Thank you.

[James]

The 305 is a non-interference motor. I have measured the valve clearance on a stock 305 head and a magnum head. On the 305 with a valve lift of approximately .450" (valve wide open) lift it will still have a minimum of .150" clearance (piston at top dead center). On the magnum head with a valve lift of approximately .450" (valve wide open) lift it will still have a minimum of .120" clearance (piston at top dead center). Hope this help.

[AZKen]

Thank you very much James.