Hi John Roth, Looking at your 2nd e-mail on heat riser for 300F, it might appear you did not receive my response to your first query? Here it is again just in case.. John Hertog Oh, yeah, those things ARE confusing, even after having done a few ! No, valve plate is smaller than bore. When cold, the spring tension should make the asbestos cushion hit against the stop. . Basically, if properly assembled, when tested in oven, they should work the way intended . When on the car, both counterweights rotate FORWARD . Check out some pictures of 300F exh. man's reassembly at lower portion of page, http://www.crossrams.com/van300f/seven.html That should help you some. Especially http://www.crossrams.com/van300f/0105exman6.JPG John