OK no heat riser. Is the timing in the ballpark and what do the plugs look like? On adding an additional cooling passage on each deck/head it is needed between cyls 3&5 and 4&6 sorta between the outer head bolt holes (I'll have to post a pic). The 2&3 I posted was meant to mean between the 2nd and the 3rd cyl rearward from the front (on each bank) which is very misleading. Almost forgot, does it heat up around town or on the interstate or both. EDIT add a 1/2" hole between these 2 head bolt holes but upward in a triangle