[DavesRide]

Yes, it has a hemisprericle gear contraption, as I will call it, at the front of cam by chain and is controlled by computer and the pressure of oil applied to it. Another brilliant idea to correct emissions by our GM theatre of designers. It has been around for a while and is used by other makes AKA variable valve timing. It makes me very fond of my HEI and carburator without the payment of a new automobile. It really does need to be addressed by a trained technician. Not just by someone with a code reader.