I got back to trying to install a repro exhaust pre heater shield on my 69 with 455 engine. I believe the reason I couldn't figure it out before is because it looks like the wrong head bolt was used by someone in the past. I imagine I must need a bolt with a stud on top so there is something to bolt the front of the shield down. I see that Ames sells new ones but i'm not sure of the length I need and given that it looks like the wrong bolt was used I'm not sure I'd trust just measuring the one that's there now. Does anyone know what length bolt should be on the lower front cylinder head? I also could use some input on whether or not I can just change out the one bolt and torque it or should I re-torque all the head bolts?
I assume I should drain the coolant before removing the old bolt correct?