i am doing a head gasket on my 89 iroc
the old gaskets appear to be in good shape ,cant really detect were it may have gone wrong
also valve s are white , and one cylinder is whistle clean,washed out
i decided to do this from a block test witch told me that there was
combustion gases in the coolant.
this car is stock
looking around for all input on this
thanks

 

It's possible that there's a hairline crack in your head gasket between a cooling jacket and the chamber. It's also slightly possible that your head is warped. Less likely though. Iron heads are difficult to warp.
Go ahead and change your head gaskets. Just make sure you put sealant where you should and to properly torque your heads in the proper torque sequence.

 

I have seen alot of 89 and 90 year model engines blow a head gasket (on the passenger side ?). I have had good luck having the heads resurfaced and replacing the gaskets.