motor is a 396 with a 454 crank (434). i had small oval port semi-closed chamber heads, 10.5:1, with an edelbrock performer rpm and a 650 holey dp. I came across some iron merlin rectangle port open chamber heads w/ 1.88/2.30 valves, 9.5:1, i put a victor jr and a 750 holey dp on it. cam is a solid flat tapet, 258 duration at .050, .615 lift, 108 lsa. im running logs and 4" risers. pump is a fresch jg with a detailed bowl and b+ stainless impeller, loader and diverter.
i was turning 5200 rpm now im down to 5000 rpm. im thinking i need to go with a smaller impeller to make up for the bigger ports and loss in compression. i know its running a little rich but not enough to loose 200 rpm in my opinion. any input is greatly appreciated.