I am running the Carter YF carb from a Ford 300 6 It is a 1953 chevy 235 babitt pounder. The motor will rev up to 4000 rpm under load tough little motor no oil pressure to speak of but runs cool I keep good oil in it. Not wanting to spend alot on this motor will replace with a 270 gmc when thats done but I feel like this motor is going to last a good long time. HEI smoothed out the rpms and starting ability when hot.