I used just standard electrical tape but I would like to use a different method sice I suspect Tape may eventually degrade with the heat that is present in the Engine Bay. I'm sure a trip to home depot could give me an idea or two. I used a piece of sheet metal cut in a small circle and use the orginal clamp to hold it in place. No blow by. I would recommend trying a copper pipe cap used in plumbing to fit over the manafold flang and just tap it in place and crimp it over the flang. There are many methods to blocking off the exaust flang I just put the sheet metal in place.