Show large product image on product detail page

My large images are all 240px width and I would like show these large product image on product detail page, rather than the pop-up.

Using 1.3.5

Any help would be appreciated.

If you set the thumbnail picture to your large picture, it will be shown on the detail page. In other words, if automatic thumbnail generation is on and you place a photo in the right hand slot, it will make a thumbnail for you and show it on the detail page. If you go in and put a larger picture in the left hand slot, and nothing on the right, it will keep those dimensions.