I recently installed an HEI into my bird with the 350 and when I set the timing, am I supposed to plug off the vacuumn advance,or is it different with the HEI?I did plug it off and set the timing to 9DBTDC,but then checked the timing after I placed the vacuumn hose on the carb and now it says like 16DBTDC.Is this correct? Any help will be greatly appreciated.Thanks