I built a chimney to replace a stinky power vent on an oil burner.Besides venting the 6-inch smoke pipe into the chimney what do I disconnect or change on the power vent?

Changing your venting system from the manufacturers instructions is not acceptable. You are asking for more trouble than it will ever be worth. You could very well be creating a deadly situation. Sorry, but I don't think you will get any help here. Time to call in an onsight pro.

Thanks for your concern,but I got an HVAC tech over this afternoon -He disconnected the powervent and I piped it into the chimney.All done-No Problem!

Glad it worked out, good call having a tech in.